Whether it’s worth it or not depends on who you are, where you live, what’s your occupation, what are your interests, abilities, existing committments, etc.
It’s too bad the other thread got closed by the mods – the one where Chinese speakers claimed, wrongly, that those who don’t bother learning the language are losers, and non-fluent speakers rightfully countered that’s a bunch of hogwash and there are plenty of other worthwhile pursuits in life that can be worth focusing on INSTEAD of studying Mandarin – too bad, because I wanted to make a point there several months ago.
The point being that the single most important factor for whether you’ll learn it or not, in my mind, is whether you’ve got incentive and motivation. If you don’t then forget it. And for years I didn’t have much incentive/motivation because I had so many other things I wanted to spend my time on and I figured I would head back to the states any time and would forget most of it anyway, so it wasn’t worth the effort.
But it finally IS worth it now for me, because my wife and I bought a house here, I finally recognized that I’m not going back for at least 5 more years, my career opportunities are vastly greater here than back home and, while I’ve worked up very nicely to a terrific position in a great company, I’ve pretty much hit the ceiling in my field for a non-fluent-Chinese speaker, but if I can improve my fluency to the level where I can communicate about serious business matters and participate in business meetings in Chinese I can almost certainly double my salary, which is what I intend to do.
So, for me it is now worth it. But for plenty of people living in Taiwan (including my former self) who wish to go for long bike rides, read novels, write novels, make music, spend time with family, do taichi, go hiking, go to the gym, or countless other perfectly valid, legitimate and worthwhile activities, such that they don’t have time to study Chinese (or even for those who simply don’t care to) for them it clearly isn’t worth it.
If one feels a need and desire to work at learning Chinese then it’s worth it. Otherwise, it’s clearly not worth it and there’s nothing wrong with that.