Meh. You can be as confident as you like, if people won't take on staff as "juniors" who are older, then the whole process of retraining - wrt career change - has been a waste of time.

I've never been involved in corporate HR, I'd want advice. Similarly, if I was doing a bungee jump for the first time I'd ask someone to check my harness ... (to spell it out, you seem to be berating someone for doing a reality check, as if reality [of the jobs market] were open to someone to define individually; ignorance and confidence can be easily confused)

Agreed. Without courage there's not much you can do.

Who's going to practice something for 10,000 hours? One who is strongly motivated to do so. Who's going to do well in school exams? One who is strongly motivated to do so (e.g. to please his parents)

Being strongly motivated is about following your own bent. Which takes courage. If you lack courage you won't even be able to perceive what that bent is. But if you have courage then you'll make your mind up and get stuck in.