the long tail of profit in a startup is wildly higher than a PhD. To be clear, I say this as one who's gone through a math PhD; none of my fellow graduates make significantly more than they would've made bypassing the PhD for industry, especially when you consider the opportunity costs. Academia is very much for people who either prefer ideas or prestige to money.

Well I am bit biased because 2/14 of my PhD class, 10 years after defending, they are >50M worth, by leveraging their expertise.

I can accept the argument that a unicorn startup might have higher tail monetary benefit compared to a PhD. But a startup job will not open as many research job opportunities as a PhD. These are typically the highest paid individual contributor jobs in companies.

Of course if managerial track is your thing, you should probably not waste your time doing a PhD.