Writing is a public work. Unless you ship it, it’s just a blueprint and blueprint can always be changed and modified. Once it’s out there, your work is going to be judged.
The readers will have opinions about your work. Most of them will be kept for themselves. Some will praise your work, but there will also be those who will hate your work and their voice will be the loudest, not because they speak loudly but because the negative voices resonate the most in your head.
Should you care?
It’s good to hear that someone values your work. It gives your work a purpose and empowers you to work more.
But, never listen to the negative comments. Never reply, never get engaged in any discussion with trolls. The job of every troll is to bring you down to their level. It’s not their fault. They have voices in their heads just like you do and their voices don’t like when someone has a different point of view and they will attack you if you think differently than they do.
The trolls are narcissists. They think that their opinion and their choices are the only ones that matter and the only ones which are right.
I’m not saying that you shouldn’t listen to all the people who have different opinions than yours; gaining a different perspective, and adopting a constructive criticism is essential for any kind of progress but just don’t listen to trolls.
It’s easy to differ a troll from a person with a different but healthy opinion; a troll will make a fun of you, he will represent himself as the person who owns the one and only right opinion, while the healthy person will simply state their opinion without any implications that you should think the same as they do.