Well, it's different thing now if luck is included.
I think that even you're not lucky but with some chance of working for strategy that someone knows, they can still win.
But if we'll be including luck, it's totally a different thing to talk about and there's no argument with that.
If it was possible that strategy generates constant income in gambling, I think lots of casinos would have closed their doors already. The whole point is that the casino has an edge and they do so in most cases. There are of course players that are more successful than others, but in aggregate I think there would be no strategy that everyone can equally apply and win.
And by the way if someone had such a strategy, I doubt that the person would be willing to share it publicly. It would make most sense for anyone to exploit it until the masses find out about it and exploit it to the extent that bookies could respond.
I agree with all that you've said, if everyone is lucky then everyone would have become a millionaire in expense of casino's lose and money.
But that's not how it goes and we know that they're a business that should make more money. If the house allows some huge wins, it's already part of their expense that they'll recover easily from the other gamblers they have.