I think that "best learning is learning from hardships" attitude comes from the need to tell ourselves "OK, it's not so bad that I'm having a hard time now, because of... something".
I also think that self-acceptance is much more important than the self-development. The self-development will come naturally once we accept ourselves.
Cheers! : )
Yes, a lot of our woes do tend to come from our tendency to "attribute externally" things that are actually about our own inner processes. And hence, working on self-acceptance is super important... after all, if you don't like yourself, how can you expect anyone else to like you?