Nice theory of hw one can’t lose.
In practice companies can go bust or get taken over at their distressed share validation level, thus fooking smart investors over.
Invest in stock market only money you can afford to lose.

After a stock market crash all shares are at "distressed" values. That's why it is called a crash.
... the banks have run out of money and are not lending any more. ...
If all the big players in the world's economy are playing the same game (run up national debt with no intention of paying it back, keep interest rates low enough the house of cards doesn't collapse) then what is going to cause that to change?
They tried the opposite a while backHas this ever been tried before? It doesn't sound like the sort of thing that will end well.
.Between 1929 and 1932, worldwide gross domestic product (GDP) fell by an estimated 15%. By comparison, worldwide GDP fell by less than 1% from 2008 to 2009 during the Great Recession.[4] Some economies started to recover by the mid-1930s. However, in many countries, the negative effects of the Great Depression lasted until the beginning of World War II - Wikipedia
Oh well, I guess they know what they're doing.

I've heard it reported that Trump couldn't care less about the size of the US debt because it's unlikely to be a problem while he's still in office. Perhaps Johnson & co are thinking along the same lines.