Not OP, but my 2 cents on this having bounced back and forth a couple of times between a founder and an employee at places. As a (co)founder life is stressful

Not OP, but my 2 cents on this having bounced back and forth a couple of times between a founder and an employee at places. As a (co)founder life is stressful for quite awhile with a lot of pressure and weight on you. Even going through funding rounds is stressful, getting the money removes certain fears and stressors but raises others, so it isn't free of issues either. Joining a FAANG company allows you to play with some technologies you may not have been able to prior, or to play at a scale you weren't able to reach and add that to your list of skills. And do so at a lower level of stress than starting over as a founder. And sometimes, people find they aren't cut out to do the founder route after doing it so this is their way out. Basically, to me it is a way to reset yourself while getting paid, learning some new skills and staying relevant while you find your next thing.