But the money wasn't his. It belonged to Alisher Usmanov, one of Russia's richest oligarchs, who had strong ties to the Kremlin. Money with that kind of provenance inspires scorn, and the kinds of deals he pursued raised suspicion that they were intended to get rid of cash.
Not so: Milner had a dream. He wanted to be in on a life-transforming business, the social media. His first US investments were in Facebook and Twitter.
According to Bloomberg Billionaires, Milner, with 12.5 per cent of DST, is now worth $3.2 billion thanks to his tech investments, which include Spotify, AirBNB, the online retailer Zalando and the mobile phone maker Xiaomi - the industry's creme de la creme.
Milner's money is a product of blind faith, so it's fitting that he should spend some of it on a project underpinned by a belief that we are not alone in the universe.
He may have had a a bigger role in driving up Silicon Valley valuations than any other investor: When "DST- style deals" became a byword, founders were empowered to demand as much as they wanted on the strength of nothing more than buzz and big user bases.
Without Milner, it's not certain Facebook would be trading at a price-to-earnings ratio of 94 and that unprofitable Spotify would be valued at $8.5 billion. The so-called "unicorns," start-ups valued at $1 billion or more at the venture capital stage, might be worth far less if Milner hadn't sought to break into the market with the brute force of Usmanov's money and his own soft touch.
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Milner helped create an anomaly that only a market cataclysm can fix. So he has the right to use his proceeds to fund another dream, that of finding extraterrestrial life by scanning radio signals from the 1 million star systems closest to Earth. (Milner says he was named after Yuri Gagarin, the first man in space). The sum involved - $100 million - is spare change to him: He paid that much for a house in Silicon Valley.
Milner's money is a product of blind faith, so it's fitting that he should spend some of it on a project underpinned by a belief that we are not alone in the universe. Perhaps tech entrepreneurs feel something of this kind on an instinctive level. Peter Thiel, who co-founded PayPal, funds research into immortality, as do Google founders Sergey Brin and Larry Page.
It may not be entirely selfless. Google trades at 34 times its earnings. It sells a lot of advertising, but its valuation is based, above all, on faith, and Brin and Page bolster that faith when they go out on a limb, financing projects with uncertain but potentially breath-taking outcomes. Someone who reaches for the stars is a visionary, not just an investor, a lucky engineer or business executive.
What if some of these long-shot bets win the jackpot? That would make everything worthwhile - the inflated valuations and the shady money, the big talk and the grumbling about billionaires dabbling in science they don't fully understand.
Leonid Bershidsky is a Berlin-based writer.
- Bloomberg