What is 'settling'?

I have so many questions going on in my head. When do you have the feeling of 'settled'? What milestone or accomplishment makes you feel so? How does one start a married life or start a family knowing that corporate culture is unstable?(one could get laid off any time). What does it take to be above middle-class/upper middle-class? When do you feel like you're acing adulting? The answers can be different for everyone and there's no correct or wrong answer. I'm going down a spiral of thoughts. I'd love to hear from you all.