In my opinion the most complicated topic about Bitcoin is the security of the wallet.

Indeed open an account and buy Bitcoins is the same as buying stocks on financial markets.

The main difference is when you have bought stocks, these are safe on your broker account, nobody can steal them.

It is not the case with the Bitcoin : the principle of public and private key is easy to understand but you are always afraid your wallet to be broken ...

And with the anonymity of transactions, you have little chance of finding the culprit