If you won $100 on the financial markets, know that someone else lost $100.
If you lose $100, know that someone else won $100.
This statement makes trading like gambling, the difference is that in trading you are playing against other traders, while in gambling you are playing against the house.
And that is not entirely true, if you trade in Bitcoin and profit, it could be from traders who want to hold Bitcoin long term, or if you buy the results from traders who are taking profits because they have been holding for a long time.
It is different from altcoins because altcoins are just speculation which makes this like gambling.
And at trading, you could make money together, while in gambling someone has to lose. When you are gambling, if you are gambling in a game that is versus the house, then the house wins no matter what on the long term, even if you turn few dollars into tens of millions of dollars, if you do not withdraw, you will lose it eventually, there is no scenario where people could make money long term.
And even if you play some game that is against others, like poker, because of the rake, everyone loses eventually, X amount of money enters the game, and less than X gets out, even the winner do not get all the money from others, but you could do that. At trading, I can buy at 10, sell you at 20, and you can sell at 30, and we both earned. That possibility doesn't exist in gambling.