40%-50% of people in the Earth were owned bitcoin by 2020. Because most of the people were still scared to scammed, they always thinking that online or digital transaction were scam especially to the old one. But I'm still hoping that most of the people in the Earth were accept the value of bitcoin.
I would like to disagree with your statement that by the year 2020 the number of bitcoin users out of the worlds total population will be that of 5 to 10% only. Saying that there will be 40% to 50% is very high and is very impossible to occur at that time of the year. But if we talk about 20 to 50 years from now possibly your computation may come true.