The biggest problem that I have with Bitcoin is that you never know what can happen with the value and that is quite bad.
You must take risk to have some actions and that is not good. You can be for sure if you are going to sell or buy it.
for example for me (and i think also other people) the value of bitcoin it's the fun part of it. I'm talking like this because of course i'm not a big hodler nor i have thousand of bitcoin. I agree whit you that some people may be scared from the volatility
Average earning person will always be scared of the price volatility as it is his hard earned money, and if price falls down he have a fear of loosing everything, and for him that small investment would be worth in millions.
i don't think how much people earn has to do anything with this.
whether or not people invest in bitcoin depends on their way of thinking. for example if they are risk takers or has any experience in any kind of trading then they will jump at the opportunity but if they are scared with no knowledge of markets whatsoever they stay away in fear and miss out.