news.verizon.net writes:

For someone who claims to teach English you have a amazing ability to not
comprehend it. He never said his son sacrificed a semester of college.

But he did. The money spent on getting a pilot's license is money that can
never be used for any other purpose, including a semester of college.

If you spend money on flying, there are other things that you cannot spend
money on. The total amount of money cannot change, so you cannot spend it on
one thing without refraining from spending it on another.

Many people may prefer the car or the semester of college, and so they do not
fly.