Even taking it one step further: what happens when a bunch of guys get bags of cash to switch schools, don't produce/start, then players who are producing want cash (because it's fair) and the entire team dynamics get jacked up? Not even schools like Texas or Ohio State can (likely) have 80 million dollar "payrolls". At some point coaches will contend with it, decide (to a degree) it's not worth it and toxic, and start to avoid some of the mess.
If a player is projected to be drafted and is already NFL caliber it seems to be a big risk jumping schools, losing playing time, and jeopardizing that status (Isheem Young). I do see the allure for a potential "star" QB making the switch as the combination of exposure and access to better talent (receivers) can maximize their own talent, increase stats, and improve draft stock. For a lot of other positions though? The risk is huge, particularly at a big school that brings in (consistent) high level talent.
Basically all a school like Iowa State can do is (continue) to produce draft picks, have success, pay guys (some) money when it's reasonable, and be honest about the risk vs reward a player has (foster trust). Ultimately if immediate money is the motivator you aren't changing their mind.