Gambling is just hoping probability comes up in your favor. You'll lose over the long term, but you could win an individual bet. Neither is under your control or can be influenced by any "inside" information. The dice don't care what you know or don't know, and bets don't change the payout.
Granted some types of "gambling" such as horse racing or sports in general are more like a prediction market than a true bet against odds, where knowing something that the general betting public doesn't know could be used to your advantage.
In sports? Perhaps you just observe a player get injured in a car accident and bet based on that.
Obviously, insider trading, but as a society we have long decided that this is evil.
And if we compare markets where I am ready to put my money where my mouth is, then this actually is called gambling. Just not a game of chance but rather game of skill.