The simple answer to a simple question; fear > greed sellers > buyers Don't bother to know the complex answer.
Because after a pump there is a dump. Always. The bigger the pump, the bigger the dump. Your question should be: How the hell did a shitcoin raise that much when it does not have any value? The answer is: Because it was artificially pumped.
It is lasting because there are suckers that buy into it. Eventually, everyone will be milked and the scam will disappear, as it has happened with many others.
For better or worse Bitcoin is loosely linked to the S&P/Dow and tends to track them. Hopefully, as time goes on, it will de-link and move more independently. As to the halving since the output has been cut in half the miners need the price to double to make the same money. It's not an immediate process and tends to take about 4-6 months for the transition.
I agree with you that people's stupidity has no limits. I wouldn't be surprised if that shitcoin goes on for another 20 years. Pumping and dumping, scamming people like OP. Because OP wouldn't have asked the initial question if he didn't believe the bullshit around the bull run after the halving.