What about Paypal? It seems to me they could really advantage of this by becoming the defacto way people use to buy Bitcoins (or at least one of the most popular methods). It's too bad they are so shortsighted about it, and only see Bitcoin as a threat.

Yes, Bitcoin is a threat, for the whole financial system for that matter, but it's much more of a threat for those who don't adopt it than for those who do. At least if Paypal adopted it, they could remain relevant in the future, and people would still use them.