I am your age and don't make nearly as much money as you do, but I am in a senior role. I find the reasons for the seeming inability to learn to be these:

1. I have no time. I am completely capped out with meetings, certification expectations, etc. 2. I am expected to perform at a high level immediately, which takes away from the ability to learn. 3. I take on stories the rest of the team doesn't want. Like right now I am digging through Auth0's library code because they don't support a feature we need.

All in all, I think the solution is to back off and start with easier task. Oh, and sleep enough and make sure your diet is fine.