To work with cryptocurrency, you need certain knowledge in this area. However, it is not enough just to learn how to work with cryptocurrency. You also need to be able to protect yourself from hackers and scammers, be able to avoid numerous mistakes that are often made by inexperienced and inattentive users. In addition, the cryptocurrency continues to develop very rapidly. Coins and tokens, according to the decision of the project team, often move to other platforms, other actions are performed, and you need to constantly monitor this and be aware of all changes, otherwise only useless numbers and symbols may remain from coins and tokens.
Many people are either too busy with other daily activities, or simply lazy. This explains why many are in no hurry to use cryptocurrency, despite its obvious advantages.
I agree with you that it is not that easy for regular people who have no idea about crypto or who are not tech savy to have problems saving their coins and put them in a secure place, but I believe that high level exchanges are not really that hard to work with. Like if they put their coins into Binance and Coinbase for example to start with and then gradually learn what to do later that would work.
I am not saying that it is the ideal spot, you may find more secure stuff, namely hardware wallets like ledger nano for example but you do not have start with that right of the bat. Learning about how you should trust the process and not get panic and keep your coins for a very long term is the real thing people should be careful about.