you can easily do it if you have a bullshit dayjob, perhaps through no fault of your own (i.e. you work for a dysfunctional organization with tons of money and no direction)

in fact... it's probably one of the best ways to launch a bootstrapped company. it's both the motivation and the sustenance to do something meaningful with your career.

most people just surreptitiously look for a new job while on the clock, or dick around until the gravy train stops, but you can also just do your easy-ass dayjob and work on your startup at night until it's time to switch.