Maybe they are confident that a team will offer them with a higher salary that their previous team are giving them. That's why they didn't sign in the first place. And it's obvious that they are looking for more money because they believed in their talent.
And they doesn't care about the business side of it. As they are thinking that team owners have a lot of money in the bag and they are willing to spend it to them. But there are exceptions and that there are players that really made that bad decision. Not over though for Kuminga, 2 years is good enough for him to show and proved that he is worth the money that he is asking.
This word “maybe” is fine if used correctly, but it should be calculated well, otherwise it can end up as a mess.
It is just like running a business, you don’t invest and start something if you don’t believe you can succeed. And it should not be based on pure belief alone, it should be backed by proper study. In his case, I don’t think they studied the situation well enough, and that is why their expectation failed. Now it is a lesson learned the hard way, because that $22 million a year he turned down will be very difficult to get back.
Aside from believing to their talent too confident, and their ego got the best of it, they sure know it happen to other players maybe they are so hard headed they don't think it will happen to them until it happen, and for sure even though they get the contract and being able to play unlike being a free-agent or no team, they have regrets over it.
Lots of players has no team because they turn down offers, remember it seems that teams are now looking for a person or player that is not hard to communicate with, if they see your attitude specially you are not a 5 star player or a player they can rely on, they will not hesitate to reject you.