You say you envy them but I'm not sure you really do. Working without feeling involvement or purpose in what you do is mind-numbing. Of course lots of people have to endure it, and some find solace in hobbies/family. But if you are the type of person who always feel you have skin in the game, I don't think you'd last a month in a position where you don't care :-D
That's an odd viewpoint. Work hands me money, some projects are interesting others less so. But, doing a good job is enjoyable even if you don't care about the end result. Like playing a sport without paying attention to the score.
It's odd only if you have not tasted it. Once you have the experience of work with a sense of purpose, working without it (if you're skilled enough to be in a position to choose) looks like an odd life choice.
I have done work I though was important, as in saving lives etc. But, it's not like I am the only person that can do this stuff. Really when someone else is paying you they could pay thousands or possibly millions of other people to do that job. The fact you happen to be the one doing it is not really important other than a sense you should not mess up.
