Because you can cover your necessities with 20% of your income doesn't mean everyone else can.
I know several people on SSI who had to take under the table jobs because their checks wont cover their food and shelter. And that's with food stamps. If they get a regular job they lose their SSI.
Ive got a friend who had to take a part time job dashing after work as a supervisor at my factory.
I think about this stuff when I'm working overtime- how lucky I am to be able to rather than have to find a second job.
I make over 6 figures as an electrician/instrumentation technician. I have a surgery coming up in September that's going to cost me 40k+. Instead of feeling it's so much and all the other things I could use that money for, I try to remind myself I'm blessed to be able to afford it without saving for years. I, again, know people who work full time and don't make that in a year.