It depends if you want to educate kids well or not. Our current model says it's not that important to educate kids - that's why, despite tripling spending in inflation adjusted terms on per student spending since the 1970's test scores on national assessment tests have been flat. That's flat as in no improvement the last fifty years despite 3x the spending - infinitesimal gain pre-covid that was wiped out by COVID.
In our current model people care about getting more money and benefits to district administrators, union officials, and companies that provide education services, but people obviously don't care about educating students well.
I think that yes, like you describe, offering substantial amounts of money would produce substantial motivation. Better, it would produce motivation exactly where needed. The poorly family in generational poverty knows they can get 20k a year if their kid studies well. The poor family pressures their kids into studying a lot and doing well in school. Yes, that's hard on the kids but the consequences are that they're well educated and their families get needed support.
By contrast, the idea that we shouldn't pay students because their families might pressure them into doing well is a false kindness. You would make school a little easier but doom the children to generational poverty all so the bureaucracy consuming our exorbitant education budget can continue to be rich.