I think you're going too deep into the thought process, honestly. You're asking 'how do you justify' this and 'how do you bring yourself to' that. It's not that complex.
Some people simply enjoy spending money.
They have 'extra' money they don't need to live, and enjoy spending it on something they like. Don't get this confused with them being charitable or giving. It only works if they spend it on themselves in some way. A family member of mine used to brag about how every three months his wife would drop 30k to repaint the bathroom, but almost in the same breath complain if other family members asked for financial help, or even advice.
Another commenter here also made a point; it's a feeling a dominating other less well off people. I feel like that has all kinds of other things associated with it though, like a general lack of said feeling anywhere else in their lives, but I'm not going into that.