Because you're taking other people's money by threat of lethal force to pursue a 4 year party vacation and getting a degree in something useless while you're at it.
"taking other people's money by threat of lethal force" in the form of taxes is seen as necessary for running society by most people, not a moral failing.
And we are not talking about "party vacations" we are talking about education. Maybe this is a commentary on the state of higher education today, but there are plenty of institutions that offer a quality educational experience here; America has the #1 university system in the world.
"a degree in something useless"
Who determines what is useless? You? Are arts degrees for instance useless? Artists don't think so. They are not typically profitable but that's a different conversation, your qualification was "useless". What makes a degree useless, who determines that, and how?
And even if we just assume a topic useless, how is giving people scholarships to study it immoral?
> Because you're taking other people's money by threat of lethal force
The government is doing that, not the dancer. If you consider general taxation immoral, fair enough, but then you're going to have to explain how a country can function without it.
> to pursue a 4 year party vacation
Boy, have I got bad news for you about a lot of students on what you'd consider more worthwhile courses.
> getting a degree in something [THAT I, PERSONALLY, CONSIDER] useless
Why is that immoral?