You couple that with maybe one day your project gets cancelled, and not due to the quality of the work itself but for other business reasons, and all of a sudden you just don't care anymore. This is something that just happened to me recently and I find it incredibly hard to get motivated to work hard on anything. I just can't "logic" my way into doing more than the bare minimum.
Let's say I am the daughter of rich parents and I inherit a fortune. It happens, am I right? For some (intuitively "right") reason, it is not considered as bad as getting "free" money from a corporation, which has intrinsically zero control over spending at the individual level. Paraphrasing some Blade Runner here, "I have seen people paid...". And while the fortune is inherited just for sheer luck (I don't think anyone has chosen their parents), most of the time those cushy positions are coming after years or decades of hard study and hard work. How many of those inheriting good money said, "I don't want it, I have no worked for it". Some, for sure. But the vast majority pocket the money, maybe do some charity or some work, and carry on.
Sure, one feeling the need to work effectively can change jobs, we all can do it. But there are many other opportunities to have a good time and good impact on the world outside of a corporate job. If the money is coming in and who's distributing the money is ok, who am I to say no to good fortune?
But I can fully understand a decision not to change to a much less paying alternative as it decreases the quality of life for an other part of every day. Considering the frightening fact that when you move away there is probably a chance that you cannot come back that easily. This may present a fear of trying out the alternatives.
If you've got kids to look after, and a mortgage to pay, it's very likely you're stuck doing whatever your doing, whether you think the work is worthwhile or not.
Most parents won't put their kids in the poorhouse because they hate their job.
If you do something quickly, and it is of high quality, it will probably get noticed, and your reward in addition to a sense of satisfaction, is more work. The satisfaction high won't override the punishment of more work, although salary will. However, salaried employees don't get paid more to do more work (bonus notwithstanding.)
Knowing that, it's not a far jump to realize that you can minimize your work but keep your salary, so long as your work output doesn't dip enough that you get fired.