The answer is easy, and it is simply because on slot games, it's multipliers are not fixed, but rather at random whereby gamblers usually plays multiple rounds at a time, unlike Sport games where it's multipliers are fixed and gamblers usually just play one round without repeating it with the mindset of hitting a jackpot. While secondly, the outcome of a slot game are always at random, whereby the longer you play, the higher your chances of winning, unlike Sport games whereby the players or team plays a major role in whatever the outcome of the match will be.

It's actually not a psychological trick but rather a result of its random effect whereby the outcome of slot games are always a product of random agorithm. Unlike Sport games whose outcome are basically a product of the team or club's performance