So here’s the question, do you believe the league itself could be the mastermind, doing this to beat the betting public? And if this is really happening but can’t be proven, what’s our approach as bettors to still make a profit from it?
IMO, it's a no.
It's impossible because there are too many of them who facilitated the event.
It could be that the leagues, teams, players, refs/umpires, broadcasters, sponsors, and betting operators would all have to be deceived. That scale of secret coordination is unlikely to be maintained without leaks in the first place.