Even if you have expertise in cybersecurity, hackers can get what they want especially if it's a group. That's why it's one of the disadvantages once crypto was adapted to be the main currency or use it as a huge business. One of the results also, people will give negative thoughts about crypto regarding this situation.
I think that cryptocurrency should be never adopted as the main currency of a country over paper notes. Though that sounds a bit outdated, but think about a whole country getting robbed by only a single exploit and by a single person- that won't be an ideal situation to fall in. So, my personal opinion is, use cryptocurrency as an alternative to paper notes, not as a replacement.