That's not even the 1%. Having enough money to never work and live solely off investment income is in the domain of ultra high net worth households, of which there are about 100,000 worldwide. So, you know, the middle class and rich is ~100,000 or so people, and the poors are 7,296,000,000. Because that's what "middle" means, apparently.
Never share an apple with Carson, moonbogg or Slew. If you ask them to cut it down the middle, they'll hand you back a strip of peel.
That's untrue, at reasonable investment return rate of 4% an investment of 1M will bring in 40k/year, so it's possible to live a comfortable life with 2M or so banked. In
2010 the top 20% of wealth holders had average financial holdings (so assets not including home, cars) of 1.7M. This suggests that the top 10% or so in terms of wealth would be in the position to live off investments indefinitely (though they may not choose to.)
That said I don't agree with slew and bogg's take on middle class - historically professionals such as doctors and lawyers were generally considered middle class, even if they needed to continue practicing their profession to live.
But I also don't agree that taking the middle 50% centered around median income is middle class. Income is only one facet of class - high income but little wealth households are not really upper class yet, they are in the position to move up through investments over time, but not yet there.
Hence I would argue middle class should be determined by both income and wealth combined. For instance a person who retired young on 1.2M in investments and owns their home (without mortgage) has an income close to median, but holding that level of wealth definitely puts them in a different social position than someone who works 2 jobs to make the median, rents or has a mortgage similar to the value of their home, and has little or no savings. Similarly, a person earning 300k/year, owning their home without mortgage, with 500K invested is not in the same place as someone making 300k/year, having a huge mortgage payment on a mcmansion, and with 30k in their 401k.
I would define middle class in a negative fashion - middle class is not lower class and also not upper class, as lower and upper classes are more easy to define.
For instance, being in the top 10% of wealth alone I think qualifies as upper class, or being in the top 20% of wealth and also 20% of income, or top 10% (or maybe even 5%) of income only, while not being in the top 20% in financial wealth.
On the other end, lower class would be in the bottom 40% of wealth and income.
Middle class would be what remains. It would encompass those with some notable wealth but not great income (say 1M or less invested and not working), those with higher incomes that do not have much wealth (so earning 150k/year salary, but not having any savings doesn't put you in the upper class), and those in between.