A friend built a startup for years and progress was not looking good. Eventually the entire development team quit and left without equities. The founder was then acquired for millions.

Another case: startup running out of money after a series B or C and a history of questionable expenses. Everybody but a few left. The founders sold their main product for cheap to some private equity firm, focused on a crappy internal tool they built and they used their last money to hire a literal army of sales people.

These sales guys were apparently amazing and somehow managed to sell the tool to a bunch of fortune 500 companies and are now making bank.

The main product they sold? It's still on life support, the original buyer just sold it to another holding.