Excellent question. I believe technology is the primary culprit. Think of something like WhatsApp, which Facebook bought for about $20 billion and would be wor

Excellent question. I believe technology is the primary culprit. Think of something like WhatsApp, which Facebook bought for about $20 billion and would be worth who-knows-how-much today. I think WhatsApp had like 70 employees, a couple founders, only took a small amount of capital, and yet created $20 billion of value in a company in just a few years. Go back a couple decades when technology couldn't scale like it can today, what would it take to create a $20 billion company? How many years, how many employees, how many suppliers, how many customers, how much capital, etc etc. Instead, it was like three guys who each made $7 billion or whatever. This word "scale" is really just code for concentration, as in, a company can grow without having to spread the wealth around, it can instead accumulate to a relatively small group of highly intelligent and creative people. Technology enables that top echelon of people to keep more for themselves. So, I would say technology in a general sense is really what's driving wealth concentration. The long-term persistency of declining rates and increasing wealth concentration tell us it has to be structural, and I'm not sure what else can explain it. But, people are often uncomfortable with this, because it's not fixable. High taxes don't fix it over time, because we can keep replaying that game over and over again and the smartest will just keep winning and amassing a disproportionate share of the wealth created.