Parlay is better in my opinion because you choose the matches yourself, while in slots you rely only on luck and nothing depends on you. Maybe such a win will go to one player out of thousands, but more often the winnings are much smaller. Parlays with high odds also win, and there are players who can repeat this more than once, but it is not for everyone and it is also difficult.
Comparing the two, parlays are indeed superior because their chances of winning can be increased through skill, whereas slots rely purely on luck. Despite this, many people are confident in finding strategies they believe will lead to big or consistent wins. Unfortunately, this doesn't lead to the desired success, but instead leads to addiction.
I believe gambling does depend on luck, but that can't be denied. The odds of winning can be increased through skill.