You're just wasting money if in the first place you've got no intention of winning your trade. Although this is similar in gambling but it's likely that people have already that common thought that when you gamble, you should be prepared to lose.
There's this thought also in trading but at least you've got certain strategies that you can apply so that you can't easily lose.
Winning in trading isn't just all relying to luck but in gambling, you can have that YOLO mentally that you will not think whether it'll win or lose as long as you've gambled and bet it like it's all up to the result.
I think you SHOULD be ready to lose when you are gambling, because gambling has house edge and that means you will lose your money, that's how gambling works, it's mathematically impossible for you to win on the long run, the longer you play, the closer you get to losing all your money. However, trading is different in it's nature because of this, there is no mathematical certainty that you will lose your money, of course if you are a bad trader then you will lose, but if you are a good one then you will win.
All gamblers lose eventually, there is a guarantee, but when trading there is none. This is why trading is not like gambling, it would never be like that, because you will end up profiting if you know what you are doing and it is not a must lose thing in the end.