Leaving a bad taste in someone’s mouth is a lot more costly than you might think.
The world is smaller than you think, and how you exit a situation matters a lot. Whenever ending a transaction, interaction, contract, arrangement, either side of employment, membership, etc. I have never once regretted erring on the side of generosity and goodwill – even if the other party didn’t reciprocate. I have regretted a few times I’ve been stingy or done only what’s minimally required.
These things have a way of coming around.