Your decisions affect others if you sign a bunch of FA to terrible contracts, then bail on the team. That world is stuck trying to fill a spot that nobody wants. And I know, you say, "I'm not going anywhere." What happens when you get a new job, have a baby, find a girlfriend, etc. You may not intend to leave, but life changes may force you to leave.
Your decisions also affect others if you make stupid trades which tears down your team and bolsters others. It increases the talent gap, which renders a world a pile of garbage if the gap gets too big.
And to be clear, I'm not saying you're doing either of these things, but you can't be so blinded as to think your decisions don't affect anyone else.