Seeker That, my friend, is what I call a "limiting belief".
My last comment ("isn't that always the way") was a sort of throw-away comment, but since you zeroed in on that, I will say that for me, it's not limiting at all. The opposite in fact. Being accepting of how things turn out, and letting go of it after it's done, helps me maintain my motivation and continued willingness to play/perform for others. IOW, because I accept it even when it doesn't go as well as I'd hoped, I am able to keep doing it.
Seeker The only way I know to get better is to practice performing by performing.
Indeed. I've written about this a lot here at PT, but I used to play for (and with) other people much more often before the pandemic, but even after pandemic restrictions starting easing, I still hadn't had the opportunity, for several years. Since last fall, I've been actively trying to create more opportunities for performing again. It's sort of working, in that, since last fall, I've played in four (formal-ish) recitals and played for guests multiple times at my house. That's more than I've performed in the last five years, but it's still less frequent than I would like, and less frequent than I need to get better at it.