I second truth be told’s point. A person only has a limited amount of time, energy, effort, etc. Seahorse you seem to be mixing two different questions: as far as your first half, I’m sure there are doctors/ lawyers/ engineeers who are frum and excited about practicing their religion BUT there are very few in my experience who are also “learners”. The time and effort that goes into both the schooling and post-school working hours of these professions make it very unlikely that they have time and Koach for real learning. Being that guys who are serious about learning understand this, they are less likely to go into those fields to begin with.
I do find that when you look at individuals in these fields who are older, you find more who are committed to learning, possibly because as you become more established you are able to have more control over your schedule. But I’m assuming you are talking about young guys.