If people sell their altcoins before the altcoin season coming, I am afraid that they will not make a big profit. But if they are willing to sell the altcoin at a current price, they will do that, and they will have bitcoin to be sold at the next high price. We will see what happens to the market, and hopefully, many altcoins can rise together to give us profit in bitcoin. If we can have many bitcoin from that, we will have the opportunity to sell bitcoin and make a big profit later.