I found this difficult to answer as I consider high income and wealth are different animals. There is relationship between the two but it's not straigtforward.
I would regard wealth as referring more to achieving financial independence (ie being able to live without needing to work or being of independent means).
I see affluence as relating to lifestyle and the income per year required to sustain it. If you borrow big you can live like a king, but not for long before it catches up!
People must be wealthy before they can be affluent. But many people want affluence before wealth. The former is financially sustainable and consistent with maintaining wealth, whereas the latter is short-term and sends you broke!
The higher your desired income, the more wealth you must have in order to derive your full income from passive means.
Even if I earned $500k/year, I would not feel wealthy at all if all that income came from an employer. Affluent yes, wealthy no! Now if I was able to save $300k/year for a few years and used this to amass a portfolio to generate enough passive income, then and only then would I be wealthy.
Stanley's 'Millionaire Next Door' book has a formula to determine your expected wealth based on your annual income and your age. The distinction is made between 'income statement affluent' (few assets for income level) and 'balance sheet affluent' (many assets for income) is a good one.
From memory, the formula was your age x your income.
If you're 30 and earn $30k your expected wealth is $90k. You're wealthy for your age/income if you've got over $180k in assets.
In contrast a 60 year old earning $100k/year with only $300k is not wealthy for their age/income.
It would be interesting to see how these compare with real Australian wealth data.
$180k is a good effort for someone on that income/age. It shows that they're a diligent investor. But $180k is nowhere near what's required for immediate financial independence even on a very basic income.
If we want early financial independence, I think we should remove the age factor. And as we're talking about money to live, why not use expenditure rather than income?
So Required Wealth to be Wealthy = Annual Expenditure x 20
That assumes your investments allow you to withdraw 5% each year after tax, costs, compensation for inflation, etc without eating into capital. If that's a bit low, maybe use 25 or 30 instead to be more conservative or accept more risk by going for higher yields.
A variant of this is ratio of passive income to expenditure. When the ratio is more than 1:1 (with an appropriate margin) you've arrived, and can 'get off' if you want to (many don't seem to, and enjoy growing our portfolios further)! This is what Kiyosaki's Cashflow game is all about.
Another measure we could use is proportion of income derived from passive sources. I think Kiyosaki talks about this in Retire Young Retire Rich.
So there are several ways of measuring wealth, but the link to income is not straightforward.
Regards, Peter