How much is enough depends entirely on your expenses, which in turn depend on where you live, because both the cost of living and the typical standard of living change between places.

If rent on a decent apartment costs nearly $4k a month, as it does in many parts of Los Angeles, for example, and if we assume you pay about a third of your budget on rent, you'd need almost $200k just to pay the annual costs ($144k) plus taxes. And that's before setting aside much for emergencies and retirement.