The guilt and pride of being important
I live in Bay Area and often talk to friends about work. For many years I was very uneasy about at-will employment, since in Europe it is notoriously hard to remove people and here you can be let-go next day (disregarding the insanity that is mass layoffs).
I remember one person said they are in a core infrastructure team and can't be replaced. I felt their confidence and I could totally believed it. They did things for years and knew the system inside out, and it was not some pet project. Another person got a new job offer and was anxious to leave their current work because they kept getting more tasks which they felt responsible for. (While this might be controversial, I am thankful they care so much about their work, because it makes my life easier by transitivity)
I also had projects where I felt I am the guy who has it all together and without whom the whole thing would collapse. It feels good. It is a major confidence booster and I believe the system is setup to make these moments happen more often, because it keeps us motivated. It also builds tech bro confidence about unrelated things.
Then I saw a "I dare them to fire me" guy quit. And things... did not collapse? Some parts quietly stopped working until it became a problem at which point they threw 3 people with no context to fix or replace it. Projects get shuffled, rewritten and rescoped and everything disappears over time. The custom hex-encoded tree data format gets tossed out for sqlite and everyone is trucking on.
Maybe we are all replaceable. And that's ok.