Where lies the frontier between sane and insane ?
Regarding this case, I don't care, I have no judgement other than "it's his life".
Living MY life is already a full time obsession
It's a tough question. I think if you read something and think "he must be mad", then maybe it's closer to insane. Like, collecting 20 mugs or something is not a big deal, but when your collection is like The Bob Dylan Archive owned by Kaiser Family Foundation and The University of Tulsa, when it raises some questions, and getting a house for 3 times of its true value only because of BD connection... I read that and think "he must be crazy".
I don't know the guy and chances are he's a great person, but facts alone make it look strange, and also he stated that it's "over the top" right there in the article. But let's face it, at least he managed to build the collection so enormous, that it certainly outlive him and will be in demand for years to come. And that's impressive.