When you spend 8 hours to gain what you might as well have gained in 8 minutes, you have wasted your time. It's not even about regret. And in a more relevant form, when you pay money to work a second job, overtime, you are wasting time.
Stop pretending hardcore MMO players are all perfectly well adjusted people with no issues in the name of rationalizing your little hobby. Why be so defensive anyway? So what if it's wasting time. Maybe you just enjoy wasting time.
By the way, the Sistine Chapel is something. A fictional language is something. Even a pornography collection, if it has an interesting theme or accentuates a surprising trend, is something. You can point to it and say "this is the product of my efforts, regardless of the value of that product, I accomplished something". What does a WoW player accomplish? The sword they looted was already there, in the game. The game they play has been designed literally in every detail. The action the player performs in order to acquire the carrot is already obvious and clear from the beginning, and it is clear what the carrot is and does. And the carrot is not even a physical object. Gaining the carrot provides absolutely no benefit of any kind, and cannot, because there is nothing to be gained, except maybe the approval of other players who are also pursuing the same worthless goal, and admire your "achievement" out of misguided envy.