I think stupid people like me never get better at chess

Everyone has a ceiling and the later you start with chess the lower that ceiling is.
Though the free and massive access to online chess, who knows. Maybe that ceiling can be raised on average and for a select few who start really early it may be raised higher than ever before.
Magnus Carlsen after all failed to break 2900 ... maybe the next generation will reach it.

If I was Magnus or aI would gladly move onto a new game or field of study. Fame money an a ego trip.

If I was in the top 100 of Chess players by rating. I would gladly go find a new mountain to scale. I stay in for the money an fame.

People with ADHD or other challenges have excelled in various fields, including chess. These conditions don't define your potential. Consistency, practice and the right strategies can help you improve significantly.
People with ADHD or other challenges have excelled in various fields, including chess. These conditions don't define your potential. Consistency, practice and the right strategies can help you improve significantly.
Agreed... in fact stats say people with ADHD or ADD tend to be on the intellectual side.
OP your lack of improvement is 80% on how you practice and study chess... the other 20% could be... I say could be nutrition, Maybe your Gluten intolerant. and you suffer from a mild case of brain fog (affecting your tactics and board vision ) or duffer from a hypo thyroid (like me) this effects brain function also. Stress... have a stressful job? That will kill your stamina to focus.
That all said... I believe one can't play Blitz (or quicker) well, without having a foundation, a foundation one can only get from playing rapid or classical. (and studying tactics and endgames... ) then you have to study opening correctly ... You can't make up your own and expect to play consistently well once you get above a certain ELO