Well look, if a guy is able to play out a contract and not a ton of it is in NLTBE incentives, then sure, it all becomes real. However you can lock money away easily to make a guy cutable amd protect the team.
Sometimes even guarantees arent guaranteed. For instance, look at Mahomes' contract. So much of it is in roster bonuses. Not that he's cutable as long as he can play, but if you put in decision dates tied to large bonuses you can get out of the contract easily in later years if something happens.