Fiat has been proven to be stable for a longer period of time since we are still using it, maybe I will believe that some investors will transfer their money in bitcoin but not to do away with fiat, they still need fiat as more than 99% in the world population are using FIAT.
Thats why an option to buy bitcoin is for those who has sapre money to do so and for a person who are well aware of internet and cryptocurrency. Still fiat is king, everyday we used it and still it it is needed in daily real life transaction. Even bitcoin is @ $10.00 fiat is still stable and important.