Paypal is king because it's the oldest e-currency around & has big capital backing it, they have 100m total accounts (of which *at least* 50-60m are active). That's still only 1.4% of the world's population even in the most optimistic scenario (all PP users belonging to unique users who have been steadily registering since the 2000's)
No man... in that case it's 10% of the population that uses any currency online.. such as VISA, Mastercard or paypal.
Not grandpa that reads news on foxnews and complains all day long about politics. in that case he wouldn't count because she doesn't buy ANYTHING online...
It's 10% of whatever the target market is.. and currently we need 10% of paypal's market... 50-60 million active... meaning we need 5-6 million from our current 100,000 or so. It will take a few years... considering Washington will come down on bitcoin a few times between now and that 5-6 million threshold.