Well, if you actually know what you're doing, you don't lose. People around here always keep saying that daytrading is stupid and you'll always lose. Other add that only big whales win, and everyone else gets ripped off. I believe there are people who know what they're doing and are successful by doing it!
Trading is a game where 95% of the people loses and 5% of the people win big. Same thing on wallstreet and in Bitcoinland. The real challenge is knowing whether you are the 95% or the 5% before you invest your time and money into trading.
There's an additional catch in Bitcoin land, even when you win in terms of fiat, you could still lose if you hold the fiat, due to Bitcoin appreciation.
Buy and Hold has been the proven successful strategy in Bitcoinland.
The best way to win at day trading is to be the whale that moves the market. That way you take out the guesswork. The one danger, of course, is if there's an even bigger whale out there that gobbles you up.