It's really good for situations where you have large groups of people that all need to informally pay a small amount of money. If you've ever organized an event

It's really good for situations where you have large groups of people that all need to informally pay a small amount of money. If you've ever organized an event like this (like say...a college party), you know how annoying it is to chase down crumpled $1 bills from people. Venmo handily solves the problem so I'm sure that's why it caught on among this demo so quickly.