Students have room in their schedules for several electives and mine has a reputation as a tough but rewarding course. The majority of my students just take a single class and go on to college to major in something else.
Kids have different hobbies. I have students who've been playing soccer since they were 5 years old who don't play around with a computer for fun. Or they don't have access to a computer. (Many of my students are on free or reduced price lunch.)
Limiting the profession to those who started naturally at a young age is a good way to keep out everyone but rich mostly-white kids with college-educated parents.