Yes, that's the basic of slots. They won't install those machines or game developers create online slots if there's no real profit behind it. As I said on other threads, the only winners in gambling in casino games are those who won a good multiplier and then quit afterward, never coming back anymore even just to try their luck again.
Winners are rare for machines that are created by humans to make a profitable income for them. Online gambling sites will also go bankrupt if they enter online slots that are like charities giving away money to gamblers.
There was once I got lucky on an online casino application in one slot provider and the next day they went to maintenance and I never won a good amount again. They will just keep tweaking the system if they see some gamblers winning.