Why do altcoins only explode in the middle and late stages of a bull market?

Funding issues: altcoin project owners lack funds throughout the entire bear market to the early stages of a bull market. They need to pay salaries and expenses every month, and can only cope with it by selling coins every month.

Fund flow: In the middle and late stages of a bull market, when big whales have made enough money on Bitcoin, some hot money will flow into the altcoin market, creating a bubble altcoin season, which is both a carnival and a wave of harvest

Shipping strategy: Directly smashing the market will result in very small shipments. Only when the market is frantically pulled during the altcoin season is the best time for each project owner to ship.