For me I would say it is important to study about security measures before investing in Bitcoin, but it doesn't mean that one should apply for online or offline course to only study much about security measures and how to buy and sell bitcoin before starting to invest.
Samlucky O, you are contradicting yourself with your statement above because you said it is important to study about security measures before investing and immediately you are saying the opposite. Learning about security measures is far too complex for a new investor and he might get scared of getting started. A new investor only need to figure out how much of his discretionary income he will use to buy bitcoin consistently and persistently without stopping for a long period of time and open an exchange account.
You have said it as it is because the study about security is an ongoing one and even till date, new measures are still being added that strengthen the existing measures. For instance, every now and then we hear about the lunch of new wallet or improvement on existing ones, the bottom-line is security. I remember when Trust Wallet was seen as the best in the market only to be revealed after a while that there were issues with it such as you said before which is it being close source. Therefore, if a newbie decided to graduate from security classes before investing in Bitcoin, he may not even graduate and may never get started with investing in Bitcoin.
To me an investor just need to put in mind that "not your keys, not your coin" and he is good to start because knowing this means he knows the importance of being in charge of the secret phrases and private keys of the storage media, hence will avoid keeping his coins in CEX and other wallets and places where those information are controlled by another entity other than the investor.