The share of national income pocketed by the top 0,1% in the US has grown from 2% to 7% since 1980. There's been nothing like the same change in any other rich country. The UK is closest, where that share has grown from 2% to 4%.
Yeah, and the ratio of incomes from the least paid in a company to the highest paid in the same company has exploded as well.

I think it is an unanticipated consequence of the stock market boom/bubble, and the well known connection between available shares and an aging baby boom population.  Money flows into the stock market, supporting the bubble, and giving companies huge capitalizations.  Management compensation, as a fraction of capitalization, is nothing ... while at the same time it is huge from a 'real world' perspective.

I was actually in a small company, and saw a couple guys turn into billionares on the day of public offering.  It was actually freakier that a couple guys who knew me, who would say hi to me (a working engineer) in the elevator, were suddenly billionares.

Why did they get that rich?  Well, they were certainly smart and hard workers ... but not even they expected that much.  It was the dot com boom, and the market just threw money at them/us.

It's a strange world.