[Question] How much slack do people have?

The question is purposefully ambiguous: I’m interested in various operationalization of “slack” as a fraction of one’s resources. I’m interested in knowing the distribution across the present human population.

It could also be that the concept is fundamentally confusing in some ways, like we all have 0 slack because any action could make the difference between reaching longevity escape velocity and not. I’m also interested in comments along those lines.