These levels seem quite broad at first but the author's reasoning is that between 1M-10M NW, at a 4% withdrawal rate it doesn't really lend you a lifestyle that is very very different. Some other tidbits below:
"Level 1. Paycheck-to-paycheck (<$10k): You are conscious of every dollar you spend. This includes people with crippling debt.
Level 2. Grocery freedom ($10k–$100k): You can buy what you want at the grocery store without worrying about your finances.
Level 3. Restaurant freedom ($100k–$1M): You can eat what you want at restaurants.
Level 4. Travel freedom ($1M–$10M): You travel when and where you want.
Level 5. House freedom ($10M–$100M): You can afford your dream home with little impact on your overall finances.
Level 6. Impact freedom ($100M+): You can use money to have a profound impact on the lives of others (e.g., buy businesses, engage in large-scale philanthropy, etc.)."
he also talks about strategies to most reliably progress out of each level.
"Unfortunately, while sensible investments will help you grow your wealth in Level 4, they are unlikely to get you to Level 5 ($10M–$100M) and beyond. The data supports this conclusion. As we will explore in more detail later, 64 percent of households in Level 4 will still be in Level 4 two decades from now. Only 8 percent of households that start in Level 4 make it to Level 5 after twenty years. Level 4 is the hardest level to break out of for good reason—the strategy needed to get out is drastically different from the strategy needed to get in.
Imagine you just hit Level 4 and you have $1 million in investments. If you don’t save another dollar and your investments return 5 percent per year (after inflation), it would take forty-seven years for you to get to $10 million. Of course, you probably aren’t going to stop saving once you hit $1 million. So let’s assume you save $100,000 after tax per year, a significant sum of money. How long would it take you to get to $10 million with a 5 percent annual return? Twenty-eight years. What about if you saved $200,000 per year? Then it would take about twenty-one years. What about if you saved $300,000 annually? It still takes seventeen years! As you can see, even with a very high-paying job (e.g., $500,000 per year or more), it will take multiple decades to get to Level 5. And note that this would be after you’ve already made it to Level 4. If you manage to get to Level 4 in your thirties or forties, this is doable, but will still require a lot of effort. Unfortunately, as I will cover later, only 5 percent of people in their thirties and 15 percent of people in their forties are in Level 4.
This is why every wealth level has a singular thing for you to focus on if you want to keep climbing. In Level 1 it’s safety. In Level 2 it’s education. In Level 3 it’s investing. In Level 4 it’s starting a business. In Level 5 it’s scaling a business. And in Level 6, it’s protecting your wealth."