Are you one?
Going out for dinner tonight with colleagues. One of them always gets right in there with a suggestion for the cheapest non-fast food option available - wherever has a special offer on that day.
Obviously you don't know everyone's financial situation, but we're not students any more. I know what this person gets paid. It's not peanuts.
If I was watching the pennies I'd see what everyone else wanted to do then make my excuses if it was too expensive for me, rather than try to take over to suit myself. Much more reasonable.