Because back in their generation, Lawyers and Doctors made the most money.

They still make alot of money, just that now other professions make equally alot.

My JC class (triple science) produced 7 doctors. I went banking route. Parents initially thought I was a failure untill they realised banking paid me about double what I could have got pursuing the medicine path.

Now, my 2nd brother is also pursuing banking (instead of medicine). Next generation, all parents will wish their kids to be bankers, lawyers, doctors.