Vesting schedule, eg, golden handcuffs, that are part of the terms of the m&a deal. They (usually) don't just hand you only a pile of stock, they want the tech founders to keep working on this thing as long as possible, so that they're a) not building something else cool that someone else will buy and b) keep any other corp from hiring them (talent m&a play).

Put up with random crap at gigacorp until you can walk away with another X deci/centimillion$.