Ask HN: How do you deal with “Not happy, but maybe I'll regret giving it up”?

Based on this xkcd: https://www.xkcd.com/1768/

(Original title, trimmed by the limit: How do you deal with a "I'm not really happy here, but maybe this is the best I can expect and I'll regret giving it up." situation?)

What is your thought process when dealing with a supbar situation and calculating risks to change it? Whether being a dead end job, a tiring relationship or a wrong life choice previously made?

What steps you approach to know if you are making the most promising decision?