Assets under management have grown significantly from 2005 to 2017 (only dropping slightly in 2008)
PE funds have outperformed the S&P 500 index throughout the 1990s and 2000s (thus generating high demand)
In the 2010's, private equity funds have become popular with pensions and endowments given their recent outperformance of public markets. This has led to a large increase in asset flows.
In the 2010's PE funds have generally underperformed the S&P 500 Index.
This coincides with a general increase in multiples paid for buying companies
This coincides with a general increase in leverage
PE forms can lift all public equity prices by overpaying for companies they take private
Even if you don't invest in PE firms, their aggregate actions can have impact on other investments you have
PE firms have raised so much money over the last decade and have to put it to work. As such, they might have to do deals that aren't super great not great for investors (circa 2018)
As PE have been successful and raise more funds, they have had to take on bigger and more risky deals to put their cash to work