Two sorts of people become billionaires from share price increases. The founders and the early investors. Neither are thousands of times more impactful than the other early hires, but they get to keep billions of dollars while the early hires only get a handful of millions. And the slightly-less-early-hires who were too late to get equity usually get nothing more than their salary, regardless of their impact.
I don't have any problem with people getting insanely rich from stock price increases, but the argument that it's society sharing the value they created ignores the fact that they were only responsible for the initial foundations of that value, and not all the work that continues later.
> Neither are thousands of times more impactful than the other early hires, but they get to keep billions of dollars while the early hires only get a handful of millions.
That's a meaningful tradeoff of risk vs. return. If you choose to be an early hire rather than founding your own risky venture, that ultimately means you value the security of "only" getting millions over a lottery ticket that might or might not be worth billions.
Society shares in the value because - insofar as the company is now worth say $X - that's because they have some way to create value that justifies a price of $Y per year for N people. And for those N people to be willing to pay $Y, they presumably have to be getting more than Y value (otherwise they wouldn't bother). So the real consumer value minus $Y is the 'value' created - the consumer surplus. Obviously there are exceptions but I think this is true in general.
And re the impact of the founders/early investors, I agree that they didn't contribute 1000s of times more. But like, if I bet a million dollars on a sports games and I get bet right and make 5 million would you say I ought to pay the players who really did the work? It's not about "adding value" its about property rights. The the second tier of engineers isn't happy they can (and sometimes do) found a competitor.