Assuming I've made up my mind to hold on to a token for many years but after a year this token hit a new ATH what should I do as a newbie? Sell or not sell?
It's wise to sell it when the value is high because you may not get such opportunity in the future. The reason people hold altcoin is basically to profit from them and once you have the profit, move to stable coin, to buy back when the value is much lesser, if you so much believe in the project. Don't be blinded by the promises of the team or developers. You should also diversify to include bitcoin in your portfolio and other more promising altcoin.