if with just 10BTC can make you become a millionaire , what about people who own 1000BTC? i think they'll be a quillionaire 
If 10 BTC made you a millionaire, then someone with 1000 BTC would be worth $100,000,000. In 2013, there were over 50,000 people who had at least $100,000,000. If you had 100,000 BTC, they would be worth $10 billion. In 2013, there were over 2000 billionaires.
10 would be fine in this scenario perhaps little more but if all calculation and prediction are in order we can expect that price goes on 5 digits so we can all be millionaires in this scenario