Second, you're assuming that even the top players would only make the minimum, which you have arbitrarily set at $200k, assuming that they would be paid less than the minimum NFL salary. The more accurate measure would be to pay them some percentage of the average NFL salary, which was $1.9 million in 2018. [1] So assuming the average college player salary would be 40% (to use your arbitrary number), that would be just under $800k per player. Even with a 53-player roster, that puts player salaries at over $40 million annually, which wipes out profits for all but the top 15 or 20 teams.
Third, I didn't say these players "aren't that good." The fact that only 2% of them make it to the NFL doesn't mean the other 98% aren't that good, it just means that the market won't bear paying for more players when they're fairly compensated.
[0] https://www.forbes.com/sites/chrissmith/2018/09/11/college-f...
[1] https://gazettereview.com/2017/03/average-nfl-player-salary/