Just run a little experiment in Excel to see what I mean. Plug in 100 numbers representing wealth in a normal distribution. Then fast forward these over say, 25 years. But the key here is that the top ~20% grow at 15%, the bottom 20% grow at 0%, and everyone in between grows at inflation so about 3%. This is generally what happens in the real world, for the most part. Watch how skewed that normal distribution becomes over 25 years.

It's not a conspiracy, it's just algebra.