Imagine how it would be easy to prevent the multimillion crypto theft if the guy only had $1,000 or so in that wallet.
It is also good to have many wallets, but according to the news, they said cryptocurrency account, that make me think probably it is an exchange. I can not have such huge amount on an exchange. If it is wallets, having a wallet with small amount of money will be better. While huge amount should be well protected, but some people will think something like theft will not happen until it is too late.
I think the unlucky guy has been in the Crypto field for a long time because the figure of $6.5 million is too much for a beginner. Don't put all your eggs in one basket, this is the best strategy to prevent the dark side that the man experienced, for example, if you have assets of $1000, it is better to store them in three or four different wallets (multisig/cold wallet).
If the assumption (according to the news) is that the cryptocurrency account is directed to the exchange, then he has made a big mistake by storing all the assets there. Ideally, he should keep a small amount of assets on the Exchange, so that if such a case occurs, he will not lose all his assets. News like this can be a valuable lesson for those who have been ignoring privacy. This case also proves why there are exceptions to the saying "not your keys, not your coins." At certain times, "your keys, your problem" can happen if you are unable to maintain your privacy safely.