Dmitry Gurski stopped writing his book about ActionScript when it reached 1,100 pages. The explanation was practical: he had reached the limit for a printed book. Most young writers have to be encouraged to keep going. Here was one who apparently required a binding constraint.
He was writing computer books between 2001 and 2005, alongside university studies. Looking back, he described a useful combination of ignorance and determination. He had underestimated the difficulty, then proved reluctant to surrender to it. There is a certain convenience in discovering how much work a project requires only after you have become too interested to leave.
Today, Gurski is the London-based co-founder and chief executive of Flo Health Inc. The company he started with his twin brother, Yuri, in 2015 crossed a $1 billion valuation in 2024. A programming manual makes an unusual opening chapter for that career. It also supplies a better introduction to his working habits than the valuation does.
A reader writes back
When Gurski shared the old books on LinkedIn, one reader had a particularly good reason to remember them. Sergey Gonchar, a co-founder of MSQRD, described learning programming from one of the volumes. When his parents restricted his computer use, he read the book and worked out applications on paper.
Years later, Gonchar helped build a company acquired by Facebook. His reply thanked Gurski for an influence that had begun well before either of them could have anticipated that outcome. A technical book had found a reader; the reader had found a vocation. This is an awkward sort of return to enter into a spreadsheet.
The exchange gives the long manual a second life. Its size looks comical until someone explains what they did with it. A reader without continuous access to a computer could carry the instructions away from the machine. The detail is a reminder that a product can be useful in circumstances its creator never pictured.
“I didn't know I was NOT SUPPOSED to write books at this age.”Dmitry Gurski, on his student years
The family business began with learning
Dmitry and Yuri grew up with a single mother who worked as a librarian. They began earning money around sixteen. That background puts the later publishing career in a pleasing family context, though a librarian’s household and a publishing business are very different arrangements.
His early work included freelance articles and books. A publisher then hired him to manage a department devoted to computing titles. The route into management passed through work he already understood: writing, explaining and helping other people learn. Executive education came later, including business study at Kozminski University and the Stanford Executive Program in 2019.
For one book, he reversed the ordinary working day, sleeping during daylight and beginning to write around nine in the evening. He remembers the absorption of writing and coding, when concentration takes over and time becomes difficult to account for. Away from work, he has named walking, gardening and fishing as ways to clear his head. The hands, apparently, still need an assignment.
When rain was a market signal
Before there were subscriptions, there were mushrooms. As a boy in Belarus, Gurski gathered them to sell. In his telling, it was an early education in a market whose supply depended on the weather and whose prices depended on how quickly everyone else arrived.
Rain brought mushrooms. It also brought other mushroom sellers. Reach the market early and the price might still be attractive; arrive after everyone had returned from the woods and abundance had become a problem. The lesson has the advantage of requiring neither a presentation deck nor a lecturer with a laser pointer.
He now retells that childhood work in the language of venture investing. The comparison is his own, and it reveals what he notices: uncertainty, timing, competition, the distance between effort and reward. Working hard in the woods could increase the basket’s contents. It could not guarantee the price at the other end.
Knowing when to make another attempt
That appetite for trying sits beside a less comfortable belief: a founder must know when to stop. Gurski has argued that a business can become a trap when it produces enough activity to survive without developing into the opportunity its founders hoped for.
The danger is easy to understand. A company with some customers and some revenue can supply an endless series of reasons to wait another quarter. Closing it means accepting an uncomfortable verdict. Keeping it alive can postpone that verdict for years, at the cost of every other thing the founders might have tried.
He describes success as connected to the number of attempts a person can make. In his account, early disappointments can create useful experience and release time for another project. This is a demanding version of persistence: it asks someone to remain committed to building while being prepared to abandon a particular build.
In 2018, he decided to concentrate on Flo. He believed the company represented an opportunity unlikely to come around twice. The sequence matters. Broad experimentation preceded a decision to focus. A portfolio of possibilities had served its purpose once one possibility warranted his full attention.
The numbers he could calculate before he could believe them
Gurski has recalled a 2017 board discussion involving three targets: 100 million monthly active users, $100 million in annual revenue and a $1 billion valuation. He could justify the ambition intellectually. Believing it emotionally was harder.
That is a more revealing admission than the usual account of an unwavering founder. A forecast can be mathematically defensible while still feeling rather embarrassing to say aloud. The person making it has to inhabit two positions at once: responsible enough to calculate, hopeful enough to continue.
When he revisited that meeting years later, he described a business with 76 million monthly active users, revenue above $200 million and a valuation beyond $1 billion. Those were his retrospective figures, attached to his recollection. The point of the memory was the gap between what a founder can put into a plan and what he feels entitled to expect.
General Atlantic’s announced minority investment valued Flo above $1 billion.
The General Atlantic investment gave the ambition a public transaction to stand beside it. The announcement also brought Jessie Cai and Tanzeen Syed onto the board. A private expectation had acquired outside capital and new people responsible for examining the decisions that followed.
Returning customers have the deciding vote
For all the size of those targets, one of Gurski’s explanations for Flo’s early promise rests on a modest observation: people came back. He has pointed to strong retention in the early product and a seed fundraising deck prepared in 2016, when Flo had existed for about six months.
A download records a decision to try something. Returning records another decision, made after experience. For a founder, that second action provides a different kind of evidence. An impressive presentation cannot make a customer repeat it. The product must earn another visit.
Gurski’s emphasis makes the early deck interesting as a working document. He was looking at a small, young company and trying to understand what its behaviour might imply at a larger scale. The argument began with an observable habit. The large numbers came after.
By January 2026, he was reporting 9.09 million new installations in a month, compared with 8.5 million in January 2025 and 6.75 million in January 2024. The repeated month gives the comparison a useful consistency. Installations remain a different measure from active use, but the series shows the continuing scale of the job.
Monthly new installations, in millions
Figures shared publicly by Gurski. Each bar represents January, not an annual total.
A suspicious view of talent
Gurski is sceptical of talent as an explanation for achievement. He has argued that what people call brilliance often follows thousands of hours of focused practice. Discussing his conversation with Harry Stebbings, he used the interviewer’s accumulated experience as an example.
There is an appealing lack of mystery in that account. Skill becomes something a person can work on, rather than a quality an audience announces after the work has succeeded. It also makes success less convenient to admire. Calling someone gifted is quick. Thinking about how they spent their time takes longer.
His public position on European entrepreneurship follows a related line. In 2025, he said he was among 125 founders supporting an initiative to encourage company building. He identified aversion to risk and reluctance to try as obstacles, rather than a shortage of talent or capital. It was an opinion about a continent, expressed in the terms of his own experience.
The young author had begun without a full appreciation of what the work would demand. The executive now argues for giving more people room to begin. Between those positions lies a career of books, ventures, partnerships and repeated decisions about where to spend the next year.
There is still something useful about that 1,100-page stopping point. Gurski did eventually stop writing. He had simply needed a concrete reason. The printer supplied one.