This question has been raised several times, and I have noticed that some people conclude that the lack of adoption is due to people not understanding Bitcoin or seeing it as a scam.
But I don't think the world still views Bitcoin as a bad thing today, though I know a lot of you thought that, but it is not the case.
I feel the reason for the low rate of adoption is just because people think it's not for them. Bitcoin has been around for over a decade, and any thought that most people would have had about it being a scam must have faded by now.
There are so many factors contributing to the low rate of Bitcoin adoption, one of the factors are the low speed of confirmation by the miners, yesterday Bitcoin blockchain was congested and my transaction took longer than usual to comfirm and the fees was too expensive as well.
Bitcoin is also still been viewed as a scam by so many people and the stories of hacking of exchanges and wallets is making people believe that Bitcoin is just a scam coins. The price dropping is also making people scared as they think they'll lose their money if they invest into Bitcoin.
This reasons and some other reason is why many people still think that Bitcoin investment isn't for them, they haven't seen any reason to make use of the coin and people are still comfortable with the banks no matter what's happening to them, people's still trust banks and the government.