Average annual tuition&fees for public 4yr universities in the US-$7020
Annual available federal Stafford loans-if dependent on parents, $3500 subsidized, $2000 unsubsidized. subsidized increases to $4500 second and third year, and to $5500 your final year. If independent, the unsub allowance is higher.
Add in Pell grants, up to $5550 per year for up to three years, EFC, and other federal, state and local or private financing options, and many, if not most can get their undergrad for free.
The situation I imagined when I read your original post is not an atypical one: a student manages to get their education paid for through a combination of grants, scholarships, parental contributions (if applicable), etc. and then has the option of taking out loans. If they have other bills to pay, or had to empty their savings, or whatever else may apply, then they should absolutely consider the loans. That is what they are there for. But if that is not the case, and they are covered and have their emergency fund intact, then I am sorry, but as unlikely as you may declare it to be (and I disagree on that), it is an abuse of the system. And taking that money and investing it is not contributing to that individuals education, but rather helping them to cultivate a nest egg. That may be nice, and perhaps we should start a push for it! I'd love to see people graduate with an eager mind and a chunk of cash to jumpstart a new business or a home purchase or whatever, but that's not what this money we're talking about is for. I doubt you would encourage anyone in that situation to pull out a personal loan from a bank and sock it away for four years, and the only difference is that we the taxpayers are paying the interest on the Stafford loan.