still I think you can't apply 50-50 term to slots, because there are cases when you get back, say, $0.8 out of your $1 bet. Is it winning or losing? Such things never happen in dice, where you either win at least a little bit, or you lose your whole bet. You can't "win" just a part of it, or your whole bet(1x multiplier) back in dice. That's why dice can be called win-or-lose, or 50-50, game, to some extent, but slots can't because there is a possibility of a draw, so to speak.
Slots are not like dice, they do not have one outcome of win or lose, there is plenty of outcomes where you may win but not get full of your wager back, or maybe you get a bit of it, or maybe profit, or maybe you profit huge, which is why people said it is not fifty fifty and that makes sense.
However there are tons of games in gambling, for example in a roulette game you have multiple options as well, in a game where you wager just red or black you nearly have the same thing (with zero making it not fully 50% on the table) yet if you pick a number, or just a place your amount of profit will go up as well as your risk. Basically speaking, gambling is not binary most of the time, it is not just 1 or 0, it is not win or lose, there are other things involved in almost all of them.