First the crash os ‘29 was caused by insane margin buying. Back then there were no restrictions and investors could margin 100% of their equities.
As for our debt? AS an old ex banker, the thinking went like this.
If you owe the bank a million dollars and can’t pay it back, you are in trouble.
But if you owe the bank a trillion dollars and can’t pay it back the bank is in trouble.
In today’s world we are the borrowers and the world (China, Japan, etc) is the bank.
If any major country in Asia (and that includes all countries in Asia from Turkey on to Japan) gets in financial meltdown mode, like always before in history the effects are felt here as well.
Nothing much to worry about at least until election 2020 is over. FED won’t raise the rates, China will pretend to keep negotiating, there are no hot wars anywhere, Putin & Trump seem to get along fine, and US consumers are spending.
If Trump loses (less likely) all hell breaks lose.
If Trump wins (more likely) China is in big trouble.
And so will be Iran and the democrats will require counseling.