It would certainly be unpleasant for many people, for many it could also mean the end of life..
A substitute for what could happen are examples of the collapse of exchanges. Perhaps the most famous example is Mt.gox. A lot of people lost a lot of money then.
At that time, much less people was interested in Bitcoin. Now, for sure, the consequences would be much worse
That's the whole point
When Mt.Gox collapsed, Bitcoin was just a toy. Back in the day it was like a casino as no one could expect or even hope how things were going to turn out in some 5 years. I'm almost certain that losing their coins was not a big deal for the majority of people then as these coins didn't cost them much anyway, if anything at all. I lost 1.5 BTC while gambling in 2014 (or early 2015), and I couldn't care less. Losing that much would be a catastrophe for me now that one bitcoin is worth almost 10k (and probably will be worth much more in a couple of months)