Time. You can be a hot shot lawyer making $500k a year and working 12 hours a day, or a software developer making $200k a year with a SaaS product working a few hours a day.
Also security. Imagine something happened and you got no income for the next 6 month. How big a deal would that be to you financially? is it "I would definitely default on my mortgage and lose my house" or "It would eat up a bit of my savings and perhaps I'll have to skip that one vacation I was planning"