Federal student loans are non-dischargeable. Also, many places run your credit to get an apartment, get a job, get a security clearance, dealers run your credit to get a car loan, etc. So while totally dropping out of the "system" is an option (i.e. becoming homeless), it is hard to have much of a life withing the "system" while not paying your bills.
If you do manage to get an apartment, find a way to commute, and get a job with blighted credit you still face having your wages garnished, or your bank accounts emptied to pay back those federal loans. No money in the bank means you then stand a good chance of not making rent, having your car repossessed, and then losing your job.
Dandy "system" we have, don't you think?
You can get income based repayment options, or get forbearance for a time, but you can't just walk away.