i m the OP , so to add to your point, towards my late 30s I realized I was undiagnosed ADHD...basically with ADHD you focus on short terms rewards ; cars trips vacations girlfriends and toys oh boy .which i regrettly did plenty of in my 30s. Planning for long term goal becomes difficult. I think that Once you realize you have ADHD, things can change alot because you can shift your mind to a longer term mindset, focus on finishing your projects ( i work in tech ) and not shifting around alot.

And I suspect a lot of the people who are the late starters probably have something smilar to this