This is very true. At least for me I have found out the hard way that I cannot predict the price of a cryptocurrency, I cannot speak for forex. I have tried every indicator that would make sense to me like trend lines, moving averages, momentum oscillators and a bunch more of others. I have lost a lot of money trying to trade well so I have concluded that a buy and hold strategy is best for me. It is more relaxing. My first longterm crypto is ETC and I am slowly buying right now. My sights are also looking at Lisk to acquire next.
Buy and hold is good approach to trading made possible by the speculative nature of cryptocurrencies. A trader's task here is to buy low and wait until it is high enough for profit and then sell. Most of the regular indicators likeRSI, Bollinger bands, trendlines,etc can be of interest here in alerting when a low price is reached and I think, we're looking at an edge we don't have with trading just the fiats.