No one knows for sure how to make $100 that way. Or maybe a professional poker player can earn $100. But as an ordinary gambler who doesn't gamble using a lot of money, it will be difficult and there will probably be huge losses if we keep pushing it. I think there may be slots players who bet over $1 and as we know, slots require luck and if you are not lucky, the $100 will soon run out. But I think there is also a slot player who only bets under $1 but can win a lot because he can really get lucky.
I think the same as you, a person cannot be lucky in any game, but it has happened that a person who plays a lot of poker, black jack or anything else, at the moment of entering a slot machine can make his balance very high, for Of course if you take advantage of the moment of luck you had, but these probabilities, although they are scarce, are possible, in my case I always play slots, but of course I am not a player like the whales who play at stake.com bitcasio.io, duelbits, among others sites, which always publish their high earnings, that is something that I personally admire a lot, but I know that to have gotten there, they had to have spent a lot of money.
Of course, some people who play poker, blackjack or even slots can get big profits because of luck. But that is very rare for most gamblers who can only get heavy losses. The casino sites you mentioned are famous casinos with many members who often gamble and spend their time there. But we don't have to follow those people who spend a lot of money because playing gambling is everyone's responsibility and we have to be able to take care of ourselves. And when we can really get big profits using little money, those are the times when we can get big luck.