Why is it not advisable to short during a bull market?

In a bull market, many cryptocurrencies are reaching new all-time highs, and the potential for upward movement is limitless, while the potential for a pullback is limited. Take Bitcoin, for example; even if it drops from 100,000 to 20,000, the decline is only 80%. However, no one can say how high it can rise in this bull market—perhaps it can reach 150,000, maybe 300,000, or even higher. Those who shorted from 50,000 until now probably don't know how many times they have been liquidated. In a bull market, one should always go long during each pullback and follow the trend.