I believe with time, cryptocurrency will surely go mainstream or adopted by many but as you mentioned the issue of high volatility needs to be tackle because it causes a lot of panic.
I believe the issue of hacking or cybersecurity can be reduced with the integration of privacy protocols used most of the privacy coins like Monero, veil, pivx etc which can make transactions untraceable and anonymous.
Gradually it will reach mainstream.
RE: Crypto Adoption is Surprising Slow. Here’s Why.