I think the one you mentioned, "Losses are part of the game" is the most important. It builds character before anything else. Strategy is the easy part since it's all in the mind, you can research, copy others, or learn through experience. But if you're not disciplined enough to accept losses, then everything you've learned becomes useless, because you won’t be able to execute your game plan properly.
People are too scared of losing or making mistakes, if anyone is trying so hard to avoid this I doubt they will ever move forward, sometimes you have to taste failure to be stronger, if you don't know how failure feels like you can't have a taste of winning either.
A soldier who goes to war was prepared to die, they look at death in the face and try to triumph, if fear kicked in you are likely not going to make it back, so yes many successful people around the world have tasted failure too many times until they break free in the end.
I have failed a lot in this crypto space especially this period of time, but I strongly believe that I will bounce back even better, and I promised to share my journey so far after this bull market is over, if anyone is reading, this is not the time to give up, standing up and falling was how life began.