Its a completely different form of entertainment, way more similar to watching tv.

The main difference is you dont need to plan or think yourself, your mind can take a break just following whats going on. This can be much more restfull and relaxing.

Compare that to activity playing the game and your using much more energy, your brain is calculating every interaction you have to make. It can be stressful at times. A loss can feel like lost time but a win gets you a high you will never get when backseat gaming.

Completely different and up to personal preference on how people like to spend their downtime.