To lose weight
>have to eat less, which literally involves no action
>can do cardio instead of super heavy-lifting
>get to save money, because you buy less food
>if you get sick, it won't interfere as much with your progress, as when someone is sick they aren't eating a lot anyways
To gain weight
>have to eat more, thus need to put in effort to organize times of the day to eat
>the need to eat more can interfere with work/school schedules
>have to constantly increase the weights you lift
>getting sick can undo 2-3 weeks wort of progress, as getting sick means you can't eat a lot
So why do so many people think losing weight is easier than gaining it? It is the exact opposite.