A bit like lucrative business opportunities, very often by the time you can enter, a million people have got in ahead of you, and the pickings are a shadow of what they were (eg flying). Law is very, very overcrowded nowadays, and medicine is getting there. Fields I can think of which are perpetually lucrative are finance and accountancy.
I certainly regret not following my fathers advice and going to KPMG after uni (ditto the offer from Chemical bank, or whatever it is called nowadays). I was an idiot and dug my heels in to go flying.
If my kid was a bit of a dullard, and would probably end up in a semi skilled mushroom position anyway, then maybe I would suggest flying.