It's currently estimated about 3 million people own some amount of Bitcoin.
That's about 0.3% of the population of Europe and North America.
If Bitcoin becomes mainstream, and say 50% of people in Europe and NA own Bitcoin, how much would it be worth?
Amount of people that own it does not matter. Demand matters. If lets say 50% of the people
want to own Bitcoin but don't have it that would drive the price insane.
Exactly! Even though every people from the UNITED STATES owns bitcoin but its only them and nobody else wants to have some, the price will not go up very much I guess. In contrast, even though only 3 people owns every bitcoin all across the globe, but the entire human race wants a piece of it, expect bitcoin to be more expensive than your life.