I think undergrads asking for money to go on a trip for school is a bit greedy
That's a strange thought. Why are you thinking about undergrads and trips?
Because I've met a student like that, and it really pissed me off.
Maybe you should mind your own business. People earn trips all the time and you don't know how the undergrads earned theirs.
You can't just ask people for money. The kid probably comes from money anyway.
Just because someone wants to have a trip doesn't mean they are a bad person. We don't know if that person had a hard time and finally wants to enjoy something. How about chatting up with them and learning about what they do, and what they are planning with the trip?