I would not be able to stand putting my entire life into the hands of bitcoin, I'd be a nervous wreck all the time. What are you totally bitcoin dependent guys going to do if we crash hard? Seems plausible still, though unlikely.
But as bitcoin becomes more and more mainstream it only makes sense that more people "only" work bitcoin. I'd say that's a good thing in the long run
It is highly unlikely it will ever go straight down to just $0 or even $less than $50 unless a huge bug was found, which would have probably by now already. But just like any investment you diversify, I own a lot different pretty safe investments. Bitcoin is the most risky of those. If bitcoin crashed I wouldn't be screwed but my future would be rocky for sure.