Here are two long term monthly charts, for QQQ and AAPL, indicating that some markets in the USA, may be going vertical at some time in the medium term.
Vertical markets are unsustainable, and are dangerous to both BUY and to SELL. A Seller is trying to SHORT a rocket, and a Buyer is trying to BUY a rocket which can run out of fuel on a dime.
The fuel needed to sustain these trends is huge, and more and more fuel must be pumped in at an ever increasing rate. This is the definition of a “ponzi” model. Those last in get to hold the bag.
These are historical market events and books will be written about it in the future.
A blow off top is expected to end it, timing unknown.