Fantastic question, Trevor. I was a student athlete in college for an unusual sport at UT- Austin (Rowing). The primary reason my sport exists at UT is because of Title IX regulations, as someone previously mentioned.
Simply put, Title IX enforces an equal number/ balance of male and female student athletes. Because UT is a huge football school with a large football team, they must include more women's sports to balance the ratio of male to female student athletes. This is why we have women's soccer, and not men's, and why we have a volleyball and rowing team. Most Power 5 universities have this- which is why you see more eccentric women's sports than men's (i.e. more women's soccer, volleyball, rowing, etc).
Most universities will prioritize the sports mentioned above (plus a few more) over extreme sports because of the lower resources, cost, and higher popularity compared to extreme sports. Money comes from donors (who mostly give their money to fund the most popular sports) and the revenue that comes from the school's most profitable sports (football, basketball ticket sales at UT for example) to fund other sports.
An extreme sport, like skateboarding, would require an entire facility to be built for practices. When comparing the cost of building a new facility versus buying a few pieces of equipment (for example, rowing would mostly need boats, oars, and rowing machines), equipment cost is far less. If you compare building a volleyball facility or soccer field versus a skatepark, you'll probably pick the sport that would have more fans to bring in more revenue.
Hopefully gives you a sense of collegiate sports and helps answer your question- I'm with you, though! I hope colleges will begin thinking about adding some new sports that are becoming more and more popular. Surfing would be really cool!