They don't trust internet with their money.
Moreover many people are also there, who thought Bitcoins are the source of Gambling, for which they often advised their own friends and families to stay away from Bitcoin.
We have gone a long way and people are not fools to not know about bitcoin, the basic problem with a common man is that if his wallet is lost or hacked he wont be getting his money back. Globally the number of online transactions has increased and how can you claim that people do not trust internet with their money, just compare the increase in the number of online transaction in the past ten years and you will understand the difference.
Basically, ignorance is what makes people lose their asset in their wallet easily.
If they are unaware towards scammers and hackers then probably they will not secure their assets much harder to prevent being a victim of it. People avoid bitcoin because they think that a digital currency or a cryptocurrency can be easily stolen or hacked from an online or digital wallet that a user utilize. But they should know that bitcoin is much easier to transact compared to fiat that undergoes a lot of process.