Is it worth trying to get better if I’m stuck at Diamond 5 after 500 hours?

I'm honestly just embarrassed I've spent so much time doing something I suck at. I've watched very many videos about fundamentals so I know what they all are but don't know the right way to do inputs in away that counts as good fundamentals. I watch my replays and I think really hard about what I could do to get better and the answer is always "I don't know." I do the drills about anti air and whiff punishing and drive impact but can't actually do those if I don't know for 100 percent sure that that's what my opponent will do. I can't tell how I can move the stick or push buttons better in a way that will make me do better than my opponents. Is there anything left to do? I'd be so proud of myself if I could hit master and keep a solid MR but I don't know if that's possible

EDIT: I'm also still stuck on platinum with all my other characters

EDIT 2: just ranked down to d4