I don’t disagree with anything you wrote. How many people stay in jobs, relationships, procrastinate personal improvement, etc. longer than they should due to the challenges and conflicts involved with jumping.
My only thought is… seems there is a business opportunity to make the jump softer. For example, what type of start-ups could help with either career advisory (assessment, facilitating reflection), or help you job search as a commissioned agent, while you are still in your current job. There may be some good ideas for new services to help people out a little more while they spend their last few months in their old job staring at the edge.