Is it worth self-funding a PhD to attend a top 10 university?
Unless you're independently wealthy I think it is always unwise to do an unfunded Ph.D. program.  With the current academic market the way that it is, there's just no guarantee that you will get a good job with the Ph.D. that will allow you to quickly pay off your debt.  There's also no guarantee that you'll get a Ph.D. at all.  We're talking about over a hundred thousand euros!  There are some advantages to a top ranked department (as ff524 says, university ranking is irrelevant), but it's not 100K euros worth of advantage (especially since often a lot of the advantage of a top dept. is that they're better funded and so students can concentrate more on research).