Leverage changes. The person you need today might need you next year. Be decent either way.

Who holds the advantage in any relationship is temporary, and it moves for ordinary reasons: people change schools, get promoted, switch teams, get good at something. Treating the current arrangement as permanent is how people end up being rude to somebody who later holds a door. Decency that depends on the balance of power is not decency, only a strategy that keeps expiring.

Notice how you talk to people who cannot do anything for you right now. If there is a difference, close it. The same applies the other way, so do not take a worse deal from someone just because they currently have the upper hand.