Hi @Joshua Milam! I had to throw my two cents in there, and this might be a little out of the box, but stick with me! I'm going to push for an engineering or some sort of STEM degree for a few reasons:
1. STEM, while having many downsides, has a ton of upsides in that it really helps you to learn how to think about the world. Whether it's engineering or physics, it teaches you how to model big ideas, and bring them down to reality.
2. If you can do the math of a STEM major, real estate modeling becomes much easier!
3. Although your friend is certain that he wants REI to be his future, it wouldn't be insane to think that someone could change their mind from when they're 18 (I know I did!!). By having a STEM degree, it'll open up a ton of jobs/opportunities outside of REI that will set them up for success no matter what path they choose to pursue.
4. A lot of folks have said it already, but there is nothing stopping you from getting a STEM degree, AND learning everything you can about REI - reading books, listening to podcasts etc. It's not one or the other!
Hope this is helpful and best of luck to your family friend!
Cheers,