I've been inside a couple of these and the founders always do
just fine. Rest and vest at the acquiring company for a couple years, earn millions in stock, found another company or go work for OpenAI as an exec.
Rank and file employees who got sub-standard pay for years at Startup get the same comp they would have got coming in the front door at BigCo. It's better than being fired I guess, but it's not some humble, charitable act by the founders. They can always wait a couple years and ride the ride again if they want.