It is hard to say whether forex trading is more or less profitable than cryptocurrency trading because it is all individual.
Surely, you should know that the markets are quite different but they still share lots of principles which are useful in all of the investing activities. I don't really see any disadvantages of forex trading, I would call them pecularities because of the fact that it is up to everyone whether to treat them like pros or cons. For example, forex market is less volatile than cryptos. Is it advantage or disadvantage? On the one hand, traders make their money because of the volatility and theoretically, the higher volatility the higher potential profits. However, there is one more correlation associated with the volatility: the higher volatility the higher risk to lose. So, forex market is more stable and consistent which I think is a pro. More than that, forex market is more regulated. There is so much scam in crypto field, in forex there is also a room for scam but it is not as widespread as in crypto market. Which is an absolute advantage.
Anyway, you can try your hand in forex trading and I believe that it is the best option for yo if you made up your mind to switch to some other market.