You're comparing the wrong thing, PayPal's market cap and Bitcoin's market cap represent different things. A more fair comparison would be payment volume, in which Bitcoin has done 15B in past 24hrs, whereas Paypal has done 100B in the last quarter.
I'd believe the 15B is transaction volume (including investors buying/selling) not payments for regular goods?
I am doubtful anyone is actually holding and transacting on clear market with BTC.