Michael Bloomberg, another billionaire, ran an even costlier campaign for the presidency. According to Politico, the former New York mayor spent in excess of $500 million before dropping out of the race this week and endorsing Joe Biden.

That amount of money is in the range of what it costs to develop a vaccine for an infectious disease. Alternatively, Bloomberg could have fully funded ProPublica, the investigative-journalism nonprofit, for roughly 20 years, or purchased a house for every homeless person in New Mexico.

The point isn’t that Steyer and Bloomberg don’t do enough for charity. Other articles about the opportunity costs of their campaigns tend to leave out that Steyer and his wife, Kat Taylor, reportedly donated $190 million to charity from 2009 to 2017, while Bloomberg donated $3.3 billion last year alone. Both men already do more for charity than the typical billionaire.

Still, their campaigns were extremely wasteful investments. At best, they produced very little value. At worst, they arguably influenced the presidential race in ways that the billionaire candidates disliked. For example, Bloomberg’s presence in the race arguably helped Bernie Sanders. Given the dismal rate of return, one can’t help but see their vanity campaigns as acts of hubris, and lament all the good that could have been done with the large amounts of money they squandered.

That’s worth noting not to demonize either of them, but as a lesson for the next billionaire who starts thinking about his or her ambitions or legacy and ponders a run for the presidency: Don’t do it! Instead, call a press conference, admit that politics tempted you, then tell the world about the awesome project you’re going to launch instead with your millions. The opportunity cost of that decision? Winning six delegates in American Samoa.