1. they can transfer immediately once and lose no eligibility 

2. they can make money off endorsements 

3. insurance after college

4. And this is  big one in my opinion, they ca return to school if they are not drafted

there are obviously more details so read the article

https://www.espn.com/college-sports/story/_/id/30957361/bill-introduced-sen-jerry-moran-allow-athlete-endorsement-deals