I guess my interpretation of hubris is different. To me, hubris is over-evaluating one’s abilities. Overconfidence. Someone who is crushed by an opponent because they over-extended their resources foolishly I would call “brought down by hubris”.

Striving to improve I would not call hubris. It’s like working out. You work out to improve—to get stronger, to feel better in your body. It’s not hubris to think that improvement is possible or desirable (IMO).