If your goal of investing is early retirement, then figuring out the absolute earliest you can retire seems pretty damn important.
Why work a single day more than you have to?

The problem is that retirement seems to be extremely complex. You don't want to leave anything to chance, so in the vast majority of cases you end up dying filthy rich, just because you need to eliminate that 1% chance you end up penniless.

There has to be a better way to narrow the possible outcomes.