Well for me it seems like you're not just talking about Bitcoin investors your idea is actually applicable to every investment not just in crypto.
To be honest with you I know few crypto investors who just wants to invest/save or hold their money in crypto rather than Fiat.
They just see it as a way to save their excess income and honestly speaking I am one of those type of investor, I just believe that it is better to keep it in crypto rather than inside my bank account.
I know the risk when it comes to price fluctuation but I really think that it is more profitable than letting it sit on my bank account.
Investing with Banks are worst ways to invest, those individual you know are doing the right thing. Since they're only investing their excess or spare money, they won't be so scared like most investors get when Bitcoin experience some corrections that isn't bad to the market since it give opportunity for individuals to buy Bitcoin as low price again. Investing in Bitcoin is risky but not investing is riskier because you'll regret it.
Good Bitcoin investors should be long term investors that want to buy and hold Bitcoin for years to benefits because if you're chasing after the short gains you won't gather wealth but when you invest for a longer period, you'll be securing your future that way.