I agree with neither of them you mention as a reason. People don't invest in crypto because they are either too irrelevant of crypto, not able to understand it, or can't do that. If they would be aware of these reason you mention, it does not matter they invest in crypto or not because they are fully aware of this market, tech at least.
There really is huge opportunity in the cryptocurrencies where peoples can really have a lot of profits but they just needs to be close to them. There are very less chances that rather than knowing the benefits and advantages of bitcoins, peoples are not getting into it. I agree with you that the peoples who do not invest into cryptos may be the one's who do not understand anything about them and also who do not trust the decentralized markets. There are a lot of peoples who invest into Stock markets turning towards Crypto markets but most of the peoples from there are yet afraid for investing into these markets as we do not know who is behind these markets and that keeps the community feel that they are not safe over here.