First of all, day trading is no more gambling than any other trading. If the price rises you ride the wave, if it doesn't you wait until it does. That's pretty much all. In this sense, if day trading is gambling, then all trading is essentially gambling. Besides, arbitrage is also day trading which involves quite a few trades (actually, twice as many) albeit it is anything but gambling.
You are incredibly wrong here and very misguided. Day trading absolutely is gambling. It is gambling because it is luck based and not based on any type of valid research or methodology. Strategies for trading assets intra-day by looking at charts do not lead to consistently outperforming the market over the long term, and there are tons of studies and data out there that show this. Almost no day traders consistently beat the market in which they are trading as a whole.
Other trading strategies are often not gambling. Long term investing is the furthest thing from gambling that you can do. Buying an asset because you see value in it and believe it will appreciate over time is the most consistent way to make money. Even trading over 1-4 month periods or so (which is most of what I do) is far from gambling because it is not luck-based but rather based on understanding the fundamentals of the asset and the market in which it is traded.
Statistically, your best trading strategy would be capitalizing on both short-term volatility and long-term growth. Since most price moves happen in a rather narrow range followed by relatively rare but big price changes, an optimal strategy would be dividing your trading capital into parts, smaller parts for catching short-term volatility, while bigger parts for capitalizing on longer-term growth.
What statistic are you talking about that suggests the best trading strategy would be capitalizing on both short term volatility and long term growth? It sounds like you are just saying the best way to trade is sell at the top of every peak and buy at the bottom of every dip. This is not realistic.
You're overall understanding of day trading (which is 100% gambling) is very flawed. Sure there is short term volatility that comes with opportunity to make money, but nobody has the information to consistently profit off of that volatility. It is essentially random noise in a larger, less random pattern.