I'm unbelievably ignorant of computer science and programming, so I don't know what those attack vectors are for PoS coins (and I haven't read anything about that topic).  I don't want to go off-topic, but I'm curious as to what those are and if they've ever compromised a PoS coin before.  I've been a fan of them for a while now--and yeah, you can call me stupid for that if you like--and I haven't heard of a PoS coin that's been hacked or attacked or what have you.

The whole "getting paid for having money" thing isn't necessarily a design flaw, nor is it a new concept.  Investors who own dividend-paying stocks get paid for holding their stock, and it's a perfect example of passive income.

But all of that aside, I'd say you answered OP's question in full.  Bitcoin's code wasn't written to be proof-of-stake, period.  I'd suggest that if OP still isn't aware of the difference, he might want to do some Googling on the subject.  Hell, I'm computer retarded (the second time I'll note that fact) and even I understand why you can't stake bitcoin.