As the world progresses, so does the quality of human life. At one time people did not know this virtual currency But now almost everyone is aware of this virtual currency.The time will come when all people will accept this cryptocurrency and start trading.Then people will no longer use this paper money. Everyone will then use cryptocurrency.
I think when the 2017/2018 Bitcoin reach new ATH around $19K, most people already know what is Bitcoin because of huge price surpass. After that, they're decide to buy Bitcoin and the sad thing is they're buy on the peak, the price continue to decrease and hit the bottom around $3K. This make them feel frustrated and call Bitcoin as a scam or ponzi etc. But after Bitcoin can make a new ATH again, this prove it's not a ponzi or failed project.