With bitcoin approaching the $10,000 mark and Coinbase, the bitcoin exchange, boasting more accounts than brokerage Charles Schwab, some pre-emptive consolation and advice are in order for people who stand to lose lots of money in a crash. First the consolation: Even if that money goes up in smoke, the investment will have helped make the world a better place. And the advice: There's a way to profit from that too, by making side bets on other applications of the technology that powers bitcoin.

That's also the case with other unprofitable projects that are losing the investors a lot of money and may lose more in the future: Tesla, Snap, Uber. Investments in them may never pay off — or may only pay off for those who cash out at the right moment, like lucky investors in a Ponzi scheme. But they pay for humanity's important advances, and for progress in entire markets.

Techcrunch columnist Jon Evans writes that unless you're an investor in the electric car company, Tesla's purpose, as far as you're concerned, is not necessarily to make money but "to pioneer fleets of smart mass-market electric cars, and the infrastructure to support them, and battery technology which is not limited to cars." He draws an analogy with the Channel Tunnel between Britain and France — a disaster for its private investors but a success as a much-used piece of infrastructure. The billions plowed by cities into Olympic preparations can also be useful in that way: The housing and sports facilities for city dwellers wouldn't have been built otherwise.