opening crates is worse than gambling IMO. why? Because you don't even know the odd of getting the mythic/arcane items that you want.

If you are gambling in a casino, at least you know the odds of the games that you play (or at least you can look it up if you don't know).

If you know the odd of getting an arcane weapon from crates is worse than winning the lottery, would you open any crates?

Moreover, there is no way to increase your odd of success unlike lottery. In lottery, you can at least buy more tickets to increase your odd, but you can't increase your odd of getting an arcane weapon when you open a crate, since each crate is independent from each other; it's like you are limited to buy 1 ticket for each lottery event.

Anyway, if you like the game and want to support STS, continue to open those crates, but you should dial down your expectation a little from these crates.