It could be due to a lot of things. Homes have appreciated in value and people are pulling money out of equity to buy stuff. A huge influx of foreign money into the U.S. markets. Some geek sitting in his basement wrote a computer program that anticipates market changes more efficiently.
Then again, it could be due to the new tax laws, lower interest rates, and increased free trade.
Or, it could be a combination of all those factors.
Thank gawd this, as of yet, hasn't become a function of government.
When the line of government assistance crosses the line to government dictation, when it comes to personal finances, then all freedom is lost.
People still have the right to be stupid with their finances and this maintains an atmosphere of person freedom.
And at the same time creates classes of the "haves" and the "have not's".