I expect most of these nouveau early retirees couldn't take a 50% drawdown with a 5-year recovery.

Indeed.
I figure the secret is owning stuff that's resilient.

Not resilient in price: any stock portfolio will drop by half from time to time. It doesn't matter what's in it, that will happen.
But some stuff will come all the way back, and some won't. If the value doesn't go away, and it's not temporarily overpriced, it's just something to wait out.

Berkshire's drawdown in the credit crunch was pretty epic, with a five year stretch without fresh highs, but that's mainly because of the price spike just before the crash.
The average price in 2008 of $119,656 (the then highest average calendar year price) was exceeded by the start of March 2010.
Despite being very cheap, the average price in 2010 was $117,757, about the same as the pre-crunch highest year.

Separately, value growth continued apace, so the value and price also went right back to the old trend. The price was not resilient in the crunch, but the investment was.

Jim