somewhere. Who owns these servers? How secure are they?

Your "spidey senses" wrt bitcoin are worth listening to.

Ask yourself, how is bitcoin validated? Gold is easy - you have it, can weigh it, etc. How do you know the bitcoin u have or are offered isnt counterfit? Currency is easy too. Now consider bitcoin: to be sure its not been already "spent" u need a full on chain of custody. U must know it is unique. U must know its not been spent elsewhere. Block chain does this. However, Wrt custody chain, imagine previous owner up the line used it for lets call it a clandestine purchase -....uh oh. Dealer of clandestine good can "throw away" the wallet, but thats risky. Something about money laundering statutes....then chain of custody is a problem...

Bitcoin not being state-linked flucuates (wildly) in value. Capital gains/losses rules come into play. State backed currencies have built in advantage here.

Bitcoin has some features of a pyramid scheme. Buyer beware.