Well, they might start using it, it's just a matter of a fact that paypal is currently this biggest monopoly online. a huge escrow service which charges huge sums and has no competitors - fucking brilliant, where do i get that job?

So why would they need, or for a matter of fact, want BTC?
I can only it how it would make them just one of many...
Since it's unregulated, and they can't risk a privileged position with governments, they don't even attempt to capitalize on it.
They are rich because no one risks to use BTC.