I suppose that the people who used to trade on forex have no advantage before the people who traded here, because forex and cryptocurrencies market are so different, that if you wanted to use your market trading skill here, they literally would not work.
it depends on which markets you were trading. Forex is ofc different but the classic Stock/Commodity markets are very similar just with much more historic data. You also have relentless strong trends, Bear phases and bull runs. Booms and Busts. It was just new that you can actually read more things by looking into order-books / understanding news.
Just keep in mind that even when people have been trading the traditional markets for several, doesn't mean they are profitable in the end. You always have to adept to new markets situations and adjust your style and expectations. Once you get to the point where you know when to step back / adjust your trades you are at the top 5%.