You can trust the casino license.
The casino does not need to cheat on slot games. If the gambler loses too quickly without ever winning, he will not play the slot again.

If you don't have a huge balance, you don't have to worry about cheating.
You have made an important point, Casino license gives confidence that no regulators will come after them but how can you verify this licence that is always displayed on their footer page, is the licence number verifiable when you search them on national business data where all business are been registered, I feel you can't trust until you verify.
what if the casino makes you win to boost your confidence in order to increase the multiplier and then you lose when you wager all your total balance. I think when a casino is very fair in all their games, they will win the heart, the soul and money of all gamblers because they will always come back.