First things first: it doesn't really mater if "it's a thing" - most of our historical wins, that we take for granted, weren't a thing until they were.

But since we're in a liberalist market economy, 'the market' here is really just business administration offering as high or low as they want, so long as there are some workers who accept it (and so long as they don't violate minimum wage laws). So if the typical worker doesn't want our real wages to spiral down, we have to play our part in shaping what is acceptable in the market. If we work together, we have a stronger voice, and can make the reasonable demand that our pay doesn't just decrease every year without reason.

I myself have no reason to do this as my life is too comfortable

Surely your life improves as the living situation of people around you improves.

For example, if you interact with people daily, and some of them aren't comfortable enough to take time off work when contagious, or to afford better food or medicine to defend against illness, or are simply more stressed in general, then that increases the odds of you getting sick. And if you're in an emergency situation and have to go to hospital (even private), less workload on the hospitals means faster and less rushed service to you. There are hundreds of other similar examples, no point in me carrying on as I'm sure you can think of a few others.