Whenever bitcoin prices take a leap mostly caused by the huge influx of money from corporate institutional investors or companies buy Bitcoin as part of their reserve assets.
For example, Grayscale Investments recently buy over 17,000 bitcoin, US payments company Square had purchased $50 million worth of bitcoin earlier this month and US tech firms Microstrategy increased its holding of bitcoin as much 38,250 worth over $500 million. you can check bitcointreasuries.org for more information.
That's why bitcoin price surge in a relatively short time but not the case for altcoins, people start to realize that bitcoin is too high-priced to make more profit compare with purchasing cheaper altcoins, then altcoins price slowly increasing following the steps of bitcoin.