It's really easy. If you directly spend more than your friend could ever afford to take from their disposable income if you switched places and while being over

It's really easy. If you directly spend more than your friend could ever afford to take from their disposable income if you switched places and while being overly emotional/drunk/etc., you're taking on the risk of hurting their dignity. Taking your friend for a ride in your expensive car should be fine, giving them the keys for a week is absolutely not. If you really want to lash out, like @ilyt said, make it invisible: spend on preparations or takedown, maybe arrange a little happy accident, or just spend normally and donate the rest to your friend's cause of choice. First world problem, if I ever saw one. Now, talking about power dynamics, meaning of work and success for interpersonal relationship, it's a whole another level of complexity that's important, but it's not just about the money.