That's pure luck indeed and we can only figure out that we are, when the slots are with us and we're winning.
Yes, it's just luck, nothing more, things are always very likely to be what they are, for me both games like crash and slots work under the same criteria of luck, except that in crash you choose the multiplier you want to win, while in slots the multiplier when you win is random and can be very juicy if you have the necessary luck.
Both are good, exciting, but I stay with the slots, for a matter of taste, and although I see that it is more likely to win in crash, because the slots offer us coins that crash does not.
Though, I would like to point out crash is also a game which is not suitable for everyone who partakes in gambling. It can generate severe feelings of anxiety, greed and desperation when one is in control on the multiplier one wants to cash out with. At least, with slots, there is not much of a choice on the multiplier we want to earn before cashing out.
I am not a fan of slots and I barely play cash, but when I do I try not to get carried away by those insane multipliers we can see on the screen, because it crashes and all out money is blown out...