When our coin price hit new ATH, i think we should sell it because it would have correction after hit new ATH.
As long as we sell with profit, i think it is OK to sell. Many people does the opposite, they panic sell because the coin price drop.
To grow our wallet, we should buy and sell with higher price than we buy it, our wallet will steady growing although with slow pace.
I agree, we should sell if it hits ATH and we make a profit. If it is a good coin, you can sell at ATH and then wait until it corrects to buy back.
We are here to make a profit so it is never wrong to sell for a profit. If it's shitcoins then don't ever buy them back after sold, with shitcoins it's very hard to repeat the ATH over and over again. For wallet growth, you should focus mainly on top coins like bitcoin, ethereum... only hold and buy when the price is low, and sell when the price is high. Your wallet is getting bigger and bigger.