>My understanding is that the correlation is very strong.
Look at the table that I shared. A very strong correlation would look like:
Bottom 20% > bottom 20% = 100%
Next 20% > Next 20% = 100%
....
Top 20% > top 20% = 100%
Pure randomness, (e.g no class impact whatsoever) would look like:
Bottom 20% > bottom 20% = 20%
Next 20% > Next 20% = 20%
....
Top 20% > top 20% = 20%
What we see is far closer to the latter than the former. Another way to put this is every single group in America is more likely to end up in a different economic quintile than the one they were born in!
>In the USA today, a child in the bottom 20% of the income distribution only has a 7% chance to ever reach the top 20% of the income distribution.
What do you think that 7% would be in an ideal world? 7% sounds small, but keep in mind that in a system where birth class had no impact whatsoever, 7% would become 3x higher to 20%. Also, keep in mind that this is the absolute worst case for all of USA and a tiny part of the big picture. E.g. the most capable 20% of the bottom 20% don't make it all the way to where they would under a fair system 60% of the time (this is about 2% of the population). Most people (numerically) have very little impact from class.
>From a purely selfish perspective, if tomorrow's Einstein is born poor in america today, its very unlikely they will ever be able to make use of their talent to aid the world.
This is hyperbolic. If they were born in the bottom 20%, and not part of the majority that bottom 20% that escape poverty, maybe. Keep in mind that the real Einstein was born into the 1% in Germany, son of a factory owner, not a chimney sweep.
>Poor people stay uneducated and poor.
This is objectively not true. Most people born in the bottom quintile escape the bottom quintile, as demonstrated by the data.
I agree that more should be done to help those borne into poverty, but this fatalistic attitude does not match reality. There are some noteworthy effects of birth class, primarily in the most extreme situations, but most Americans are unaffected. For those borne into poverty, we know what factors generally increase mobility. If you stay in school, off of drugs, and keep a clean criminal record, chances are very likely you will escape the bottom quintile. I think more effort should go into helping people do these simple things, and less effort should be spent spreading the idea that outcomes are determined by birth.