Being sad or living a miserable life is a choice. The reason for it could be anything from a job to a relationship.
I find it weird when people crib about their toxic work environment and how they are barely keeping up with their health. In the same conversation they mention, pay is great so they are continuing at it for their better future.
I also find it weird seeing friends continue to live in failed relationships because they are used to each other. Both sides have given up in finding a truce or moving on.
We are letting Sunk Cost fallacy dictate in most scenario. As a rational human, the Opportunity cost is what we should be caring for.
People are frugal in guarding their personal property; but as soon as it comes to squandering time they are most wasteful of the one thing in which it is right to be stingy.