It's not all tennis or all career post grad. UTR has created a series of their own pro tourneys that are round robin where collegians, pros, juniors can earn $400-$3k for 15-20 hours of play (4-5 matches). While no ATP points are earned, the $ are better than Futures for most players. Even finishing 8th is around $1K. Lose in 1st rd of Future MD $25K after qualifying, and that's only about $250 earned. Let's say a grad takes a career job in a strong tennis area-he/she can supplement main job with paid hits, weekend coaching, prize $ tourneys, PTT events, etc and still keep up tennis level. If a player/worker works remote or has a flexible job, grad could even possibly travel and play Futures too. Now obviously that player will not be aiming for top 100 ATP but their college experience may allow them to pursue tennis as a fun side hustle with a decent return. When my son worked career related summer internships, he talked with his work supervisor and local TDs so he could fit in local prize $ tourneys-he'd go into work at 7am, leave at 4pm, arrange for his matches to be played 5;30ish etc. If a player is a seed for a tourney (top 4 or top 8 in a draw of 20-32), the TDs will usually try to accommodate player schedules. There have even been college players playing those PTT tourneys during final exam weeks-scheduling matches around exam schedules, earning $100-500 per match depending on results, and still earning the high grades. Tennis players are smart, disciplined, and adept at multi-tasking.
The players who are serious about their academics are probably not taking away the chance of someone who can do something in tennis. Those 100% tennis players are probably taking mostly online courses in fall (or taking fall off), playing Futures in the fall, and playing high in the lineup for the college team in spring. The guys balancing academics and tennis are probably only playing 1-2 Futures in fall. It doesnt really matter how many Futures a player plays, but how far he/she gets. I remember one US collegian who was top 10 jr iTF but it took him 15 Futures to win his 1st ATP point-USTA wasted WCs on him as junior.
Players are passionate about tennis. I can think of several players who had great jobs in IB/Finance etc, quit after 1-2 years to go into college coaching, being pro hitting partners, etc. Even if college grads know that cant make it on the tour, many like to keep a toe in the water-playing just enough Futures to qualify for a few the following year. So few can make $ on tour, it's great that there are more options besides the ATP/WTA for college grads to earn tennis $ even if it is not their main career.
Some reasons why international players who arent ready for tour still dont choose to play college: 1)almost no clay tourneys in college (think there is one in FL and one in Milwaukee in Fall)-Europeans may be clay specialists (this does not affect US players that much-mainly FL players are good on clay), 2) difference in scoring ( pro matches are longer with ads, college matches may not build endurance needed for pro matches), 3)college team atmosphere with chirping fans/not playing opponents is totally different from Future audience of a handful of fans-most international players adapt but some may not. I watched a fall invite and one of the better players at the event in Sept was back in Eastern Europe playing PTT events a month later and then Futures in the spring-he only played 2 college fall events before returning home. Now not ready for prime time players have two options: college then futures or PTT tour then Futures. Of course those in college, can play Futures and PTT while still in college.