When you day trade, even if it's for a few hours, you own a piece of something. It's a physical purchase of a company. You can choose to hold it forever, sell it, etc etc, but the fact remains, you OWN a piece of that company. I buy a share of Apple, I own that fraction of the company as an investor, even for a few hours/days. Furthermore, a day trader can choose to hold the stock for longer if the stock dropped that day, but he/she feels that it is still profitable. When you pay into a tournament, you don't "own" a share of the player. You are choosing how he will perform in a sporting contest, a result which is entirely left to chance. Once the entry fee is paid, you are at the mercy of chance.
Yes, I understand your broad point, that chance exists in each field, but this isn't apples and oranges in terms of a comparison. The stock market seems like a gamble, but it is a proven commodity. I support people's right to spend their money how they choose 100%, be it online poker, DFS, or any other measure, but I draw the line at calling DFS "not gambling." Fantasy sports, to a degree, has always been gambling, whether it is short term or long term. The problem isn't what it is being called, the problem is that not enough important people are making money off of it. And that's bad. I say this from the perspective of a former online poker player who has already been through that battle.