I've lived on approximately $20,000. for most of my adult life. I did have a year when my income went up 33% and I spent it all. (I wasn't aware or responsible with my spending at that stage of my life.) I've not been a high earner, but have always kept my expenses low. I still make it a goal to live on half of my budget. I try to live on $1,000. a month. I don't, but it keeps me in check. I've backed into retirement unexpectedly. I inherited some money, and I have a 567 square foot house. I bought it for $89,500. My dad taught me to only live on the interest of any money you inherit. Because my home has increased in value, I've been able to achieve that on paper. I read books on how people survived in the Depression and I use their techniques. I have a nice plot of land and I grow all types of fruit. (That was my biggest grocery expense.) I knit my own clothes, but sell a lot of what I make. I turned the hobby into a home based business. Quality yarn is expensive, so this way I stay on top of those costs. This has also almost eliminated what I spent on clothes. Anything else I buy brand new at the Salvation Army. (except shoes.) They have a lot of really nice clothes donated from stores that have gone out of business. The tags are still on them. I take care of my things so they last forever.
When you retire, your expenses really drop. No more commute, or need for work clothes. Your car needs less oil changes, repairs, etc. I ride the bike a lot, and use the car once a week. I mend my clothes, darn my socks, and cook everything from scratch. I like doing all that stuff.
I've found that the saying "Money follows money" is true. I also believe debt creates debt. The formulas work, regardless of your income. Low earners spend a lot less in taxes and (in America,) health insurance.