Use it to trade, though it is a little risk but try it.
If he really wants to do that, it would be better to use just part of it. That is a lot already and buying some sold out coins that stands to be a good project at the dip and selling them when there is a bull rally or FOMO rush on the coin to catch some profit, is always the best time to always drop them and look for the next target before coming back to that one once it finds a bottom. 600k though is a good amount of money and the OP can decide to set up any business offline which may not even have anything to do with crypto.
Obviously, not everyone would have been able to stand to say they have made so much like that after some couple of years. It is addictive, crypto, success, and so on as you will always want to make more as much as possible, so calling it quit, is one thing I doubt if anyone will ever do. For that kind of money for someone like me, I am just starting as I have not even reached any stage.
