Have you forgotten the very reason for Bitcoin? It was to serve as a payment method for any type of transaction. But the problem is that its value had risen that we had forgotten its main reason why it was built.
He ask how many people will invest on bitcoin he will not ask what was the reason why we here in bitcoin? It is true that bitcoin can serve as a payment aside from that we can earn profit in different ways like joining signature campaign, bounties and twitter campaign. But no one knows how many traders have in bitcoin especially bitcoin is very popular now. I think not less than in a million users because there are some countries banned bitcoin because of their different reasons.