Annie Mueller wrote up some excellent (and timely) advice on being more confident:

Mess it up badly.

I mean, just fuck it up completely. Do irreparable damage. Leave things a total mess, preferably bloody. Look back on your prior crashing-and-burning with a certain fondness. How petty it seems in comparison to the absolute destruction you’re standing in now. How easy it was, in retrospect, to recover. How small a mess, really.