It depends on the coin as well and how bottom are we talking. Like, if you are holding shitcoins or some coins similar to that, and you realise that these coins are shit and are losing their value very rapidly, then it’s better to sell them at the bottom rather than stalking them up until they are completely dead and are left in your wallet for eternity. But if you are holding some well-known coin, that you have faith in, then it’s better not to sell them at the bottom as they the potential of getting a bump in their price, and having an increase in them, so it’s better to be patient with them.