The way I look at gambling and trading is this:
In gambling, the house always has an edge. It varies by game, but they always have an edge. If they have a 1% edge, then for every million dollars bet, they will get $10,000 in revenue. If they run $100 million through that game, they will get $1 million in revenue.
In casinos, some people win big, some people lose big. But statistically, the house knows that its edge will bring in the revenue. As a gambler against the house, you cannot get around it. You can, however, play games that have the least house edge and you can use prudent risk and money management to make a living gambling. It is possible and there are guys doing it. But that does not mean the house will still not get its revenue from others, like Aunt Martha and Cousin Bob.
With trading, I am the house. I have the edge (side note: if you don't have an edge, you should not be trading). Your edge could be a particular setup that works 58% of the time. That's an edge. You could have a setup that works only 30% of the time, but your edge is taking frequent small stops and riding very large gains when you are right. That's a legitimate edge.
The point is, trading is like owning a casino. It is not like being a casino customer.
That's why I get a little ruffled when uninformed people (usually well-meaning friends or relatives) say "Trading is gambling." They are, of course, correct. But in Vegas, the house gambles, too -- against the customers. Do they lose? Of course not. They have an edge.
Gotta have an edge. That's the grail.
-- Dave