you can earn bitcoin in a very very fast if you play in gambling, but earning bitcoin from gambling is very very risky,
That's right you can earn bitcoin very very fast from gambling but you can lose your bitcoin very very fast in gambling too. well,that is very balanced in my minds. Trading has always become the best way ever. 
And about trading , that's good idea even you choose wrong coin you still have your bitcoin not all of your money loss (cut loss)
In line with you, gambling is different from trading. If we gamble and lose then all bets we lost. In contrast to trading, although we lose, it is unlikely to lose all the money because you said right there cutloss to reduce our losses. Thank you