If Bitcoin price pumps from $1300 to $3000 in few hours, nobody would make profit from it, because the exchanges wouldn't allow you to sell your Bitcoins and make the fast profit, it would bring a big loss for exchange sites.
Do you agree with this?
Exchanger still make profit from fees. I think one who hold bitcoin will buy dollars when bitcoin is in the peak price, and wait bitcoin to fall again. When the bitcoin is lower they begin to buy bitcoin again. I think only the lucky ones who can predict will gain profit.
While there is some luck to the market (and in fact there is a lot due to the hair-trigger sell button usage from some bigger holders at the sign of any kind of bads news), there is some merit to looking at the market and making haphazard guesses on where the market is going to go in the future. It isn't entirely based on luck, but it doesn't exactly have large margins of error either.
A lot of people can make money, but often it is a zero-sum game and you don't want to be on the losing end.
Bitcoin is big enough so the predictions of technical analysis can work on it but at the same time bitcoin is small enough to still being manipulated by the whales and that is why we see such wild swings in one direction of the other and if you are in the opposite side of what the whales want to do you will find yourself with heavy losses very rapidly.