Why Are Corporate Profits So High?

Because wage growth is so miniscule:

U.S. businesses have never had it so good.
Corporate cash piles have never been bigger, either in dollar terms or as a share of the economy.
The labor market, meanwhile, is still millions of jobs short of where it was before the global financial crisis first erupted over six years ago.
Coincidence?
Not in the slightest, according to Jan Hatzius, chief U.S. economist at Goldman Sachs:

“The strength (in profits) is directly related to the weakness in hourly wages, which are still growing at just a 2% nominal pace. The weakness of wages and the resulting strength of profits are telling signs that the US labor market is still far from full employment.

Want to know when the stock market will go way down?  When that profits as a percent of GDP chart reverts to the mean.  But that may be a while:

So, corporate profits are their highest ever and wage growth is near its lowest in half a century. But don’t expect the transfer of that cash from businesses to workers to start any time soon, says Hatzius:
“The bottom line is that the favorable environment for corporate profits should persist for some time yet, and the case for an acceleration in the near term is strong. Hourly labor costs would need to grow more than 4% to eat into margins on a systematic basis. Such a strong acceleration still seems to be at least a couple of years off.”

However, it will happen at some point.