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Indeed, you can claim that we should compare the net result with the base bet, but then I can say that you should be winning all the time (in net total), otherwise you get busted somewhere within this sequence of 10k rolls, and probably not just once. Either way, 40 bets a month doesn't say a lot on its own (apart from luck still playing a role)
If you agree that in betting 20 years in a row, 40 bets a month, luck still playing a role, than, I think, you can also agree that there can be several gamblers, out of 1.6 billion, who are lucky enough to be in profit from their gambling during this, pretty long, period of time. And that's my point, not
everyone loses to gambling in the long run
I agree that there are lucky guys
And I agree that as long as luck plays a certain role in the outcomes (read, as long as you don't make millions of bets
and go for high wins), you can be that lucky guy. Moreover, given the number of people allegedly gambling every year (it doesn't really matter since we can just assume that they are for our thought experiment), it is also possible that there might in fact be a few people who could arguably be considered extremely lucky (read, statistical outliers now having their say due to bet outcomes following the law of large numbers)
However, you omit another detail from your story. Basically, your story implicitly assumes that everyone out 1.6 billion people are betting exactly that way. But this is simply not known to us, and unlikely if you ask me. In other words, to make your narrative look plausible, you should have all 1.6 billion people bet the same way in the same long run. Otherwise, it all comes down to what we have already established, i.e. as long as luck is capable of prevailing over the house edge, you can be lucky enough to win big. But we already knew it long before this discussion
Btw, it doesn't matter whether it's 2x or 10x multiplier. Having not much time, I just made only 2k bets, but I think you can get the idea
In fact, it does matter a lot
With a 10x multiplier, you are set to struggle with extreme variance, with the implication being that you are going to lose your balance not so much due to the house edge, but specifically due to bad luck. Really, if there is good luck, there should also be bad luck, right? And just as good luck helps you increase your balance, the bad variety will help you lose it, with no house edge involved in the process at all. But once you lose your balance, there's no way back (read, it is a gameover for you)