This is not advice, only some notes on my experience. At the age of 40 I became a student at what I still consider to be an absolute top class flying school: baesystems in Jerez. It had been a lifelong dream which got put off forever until I virtually won the entire fee for their integrated course. (It was a share option thing.)
In my time there, which was one of the most challenging and rewarding experiences of my life, I rattled through all the ground school exams first time (hard work of course but not rocket science), got my CPL first time but then struggled with my IR. I did pass the 170 first time but by the time I got to the real thing, I was all out of luck and failed my IR. For another crack at a series, I had to withdraw from the college temporarily to either earn some more money or worst option borrow some.
It was only when I left, that I had a chance to stand back and look at where I really was. If I went back and passed the IR, what were my likely career options in aviation at the age of 42? Best/only guess - flying instructor. Then maybe air-taxi (after I built up over 700 hours PIC), then maybe a shot at turbo-props and then who knows a jet job.
But I knew all this before I joined, I just didn't want to think too much about it. Well you might ask, what is so bad about that route? Not much wrong about it if you don't have a long term relationship, have no responsibilities and are not used to £40k+ a year. At the age of 42, when I left the college in Spain, I did have a long term relationship and had been used to £40k+ a year for many a year. I was not really interested in losing either. If I had taken some poorly paid instructor job too many miles from home, we simply could not have managed: personally or financially. Same is true for any potential air-taxi job.
Some of the ageing wannabees out there (IT and engineering seem to host the most) may be bored with their well paid jobs. They may take for granted their good salaries, nice houses and enviable cars. They may have forgotten the hard slog and the many years on their CV's that got them where they are now. I know I did. But looking back I don't regret it. I got to take a big chunk of time off, do something I always wanted to do and in the end return to what I do best.
Bottom line for me, not for anyone else, is not so much that I was too old. It was that I could not sacrifice my very happy personal life just for flying. If I won the lottery tomorrow and did not have to worry about losing earnings or the cost of re-training, I would go back and finish the IR. But I won't win the lottery, so I won’t go back.
I still love flying. I will never lose that. But in this lifetime, it will be in Warrior’s or 172’s in my spare time.
No advice, just my experience.