Feedback from a not-high income earner here. I'm FIRE now and did most of my groundwork long before Pete became MMM.
Savings rate, as others have mentioned, is just a measuring tool, and not a particularly accurate one*. After a career in sales, I can assure you, it's the dollars that matter most, not the percentages. The way you deploy those dollars has a significant impact on reaching FI. If you invest early and well, your savings percentage becomes even less significant. (This is what the pay the mortgage off first, then save contingent just doesn't understand.) The earlier you shovel money into retirement and low-cost equity accounts, the smaller the shovel you will need. If you save a huge percentage of your income, but you don't invest it well, you're not necessarily better off, because inflation will always nibble at your money.
*For example, some people count their employer's contribution in their savings rate. IMO, this is totally cheating. Worse still, it's like cheating at Solitaire. The only one you're hurting is yourself. Worry about the number of actual dollars you are amassing and how you are investing them. The results will speak for themselves.