Firstly i introduced with crypto world by one of my Facebook friends. That time it was for me only a place to make money. But the more i got involved in this world i realized its a reveluctionary tech which can change the world financial system completly. I can not say its future but i can predicted that it can be an alternative of paper money.
You're right fiat money or paper money could both co exist with btc and other cryptocurrency. We have almost the same situation on how I get into cryptocurrency. I have a friend in facebook who introduced me how btc work and how i can able to earn from it. I didn't believe him at first but I found my way in with my own research.
I prefer having them both too, although I really hate banking system, but doesn't mean that I hate paper money, I just hate how banks are controlling our money and they are questioning us if wanted to withdraw large amount of money which is for me not really good one, they should not care about it anymore.