Anyone ever pay for friends who don't have credit cards and have them pay you back for extra points?

One of my friends who isn't in the credit card game recently bought a new Macbook pro that was on sale. Only card he has is a C1 Platinum with 0 rewards. I went with him to Best Buy and copped an easy 4800 points paying with my USBAR and he venmoed me back right afterwards.

I always do this when going out to eat with people too, I'll pay the bill with my Gold card and have everyone pay me back instead of splitting the bill.

Anyone do this too?