I wouldnt trust anybody but myself and my own research, but i would maybe take some profits. =)
25% of profitt from all coins to new coins you strongly believe in - then let the market repeat itself.
600k in crypto is quite a huge profit, but I dont think it is a good reason to quit. If I was the one, I wouldnt quit immediately, I will simply withdraw the profit Ive made so far and start afresh and make more money. #600k is even a small amount of money compared to what Im seeing people make from Bitcoin. There are people making millions of dollars from this, but dont be greedy lol.
At the end is his call if he lives in a poor country that may be enough to retire and live a good life if he lives in the first world then that is a good amount but nothing close enough to retire, but he seems to be talented since he has made so much money in such a short amount of time, I made some money but nothing even close to that so I do not see any reason for him to quit.