Since 1981 US Government long term debt has continued a steady decline of interest rates after having a previous 30+ trend of rising rates leading to the 14% in 1981. It has been a consistent decline in interest rates over the past 30+ years and since 2008, led by purchases of the US government, even in the face of the US Government more than doubling the supply of US government debt to 20 trillion the last 10 years, long term rates are still at historic lows.
By Central Bank policy, interest rates have been a constant force for improvement in stock prices, eliminating the competition from bonds. Investors have come to view this as "normal" activity and the need to even consider the reasons of WHY to own a stock is now commonly viewed as foolish by the average investor in the stock market. There are plenty of individuals who do not trust the market but for the most part they are not part of the stock party.
In 1981 the US stock market capitalization was 40 percent of GDP, since then it increased steadily to 144 percent of GDP by the end of 1999. At the nadir in 2009 it came to earth at 95 % of GDP, it is now back at peak 146% of GDP. In 2009 GDP was 14.5 trillion, now it is around 18 trillion, not very much GDP bang for 10 trillion in debt spending by the government over that time.
All of the talk of the types of stock ownership and how it is acquired has had no effect on the long term performance of the stock market. If the market were to go into a prolonged stock market decline Zweig would be arguing the constant selling by target date funds is keeping the market from rallying. The simple truth is stocks are in demand because bonds are not competitive and are not being offered for sale even as their supply is swelling.
Mathematics or block chain currencies at some point will force the hand of Central Banks, and any purchases, sales due to the composition of retirement year funds will have little impact on a long term chart of stock prices once interest rates revert to the economic value they are intended to provide. Imagine for a moment what would happen to Central Bank policy if suddenly APPLE announced they were converting their 50 Billion US dollars into BITCOINS.
The effect of this low cost debt has been to subsidize debt investments in new technologies which is drastically lowering prices and preventing inflation, which is needed to offset the increase in debt.
Could the stock market get to 300% of GDP and US Government debt get to 40 trillion over the next 10 years keeping the economy on its upward path of 2-3 percent per year, all while 10 year rates slowly grind to 5 percent or whatever a true economic interest rate for the 10 year would be, doubtful...
https://www.thebalance.com/us-gdp-by-year-3305543
https://fred.stlouisfed.org/series/DDDM01USA156NWDB
