There is no financial advisor worth his/her salt that would ever recommend a top 5 player foregoing the NBA for a year.
I think you are trying to make fetch happen. It won’t.
If you are just dealing with this at the contract level (whether employee or not) you will run up against the irreparable injury rule. Players can pay buy-outs to get out of the contracts.
If you actually want to stop player movement every year, then you need enforceable CBA's and a...
Saying the Strait is "safe" for a destroyer to pass is not exactly the same as saying the straight is "safe" for a slow-moving cargo ship with highly flammable cargo.
The problem is that Caleb would then have to wait an extra year for his second contract - potentially costing him tens of millions of dollars. No rational person would do that.
Like many things we do in America, the way we do it isn't because it is the best way of doing things. We do it that way because we we used to do it that way.
If we were building a minor league sports system from scratch, we wouldn't go through the universities. But that ship sailed long ago...
They’ve been in that business since the 1950s - and really in that business since the 1980s. The players are now sharing in that business, which makes plausible deniability harder.