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?
You need make a limit on how many percent you wanted to earn before selling it. Don't ever think that if you still hold it you will gain a big profit, remember that the cryptocurrency is high on volatility so there is a possibility that after reaching a new ATH it will fall down and you will loss, so if there is an opportunity of earning small or big earnings grab it.