So, when you are saying stuff like "30 bitcoin should lose 0.3, if you give them 0.2 there is an expected loss". Hence in the long run if you wager 30 bitcoin and win 30 bitcoin, that's unexpected, if you wager 30 bitcoin and lose 30 bitcoin that is unexpected as well. We can't calculate things with unexpected results, we can't calculate it like that is possibility, when you wager 30 bitcoin the worst is losing all of it, but the win has unlimited possibilities, which is why we drop it down to one thing we can calculate; house edge.
That's an interesting observation! I have a feeling that I never gave it a thought(or maybe I forgot, idk). Anyway, indeed, you can't lose more than you have on your balance, but what you can win, theoretically, has no upper limit!
Like maybe you can start with 30 bitcoin, make it 50 bitcoin, and lose it all, which means you still lose your own 30 bitcoin, but you are also losing a potential 50 bitcoin withdrawal instead as well. It means I am both right and wrong, yes you only lose what you deposit and not more, but would you consider potential profits as loss as well when they are gone? That is a question to be asked and I am sure everyone would have a different answers.
And that is gambling's basics, that is why I never really deposit too much, from 10 bucks to 50 bucks and that's it, I rarely ever ever deposit anything more ever because if I do I would lose it and I know it, but if I deposit less, all I can lose is that amount and that's it.