In fanfiction there is a difference between being a good writer and a popular writer. 

because you can write a well-structured story with dynamic and consistent writing and characters doesn’t mean you will be popular. And sometimes
stories that have disorganized plots, mediocre writing, and/or OOC characters will be held up as
the greatest things to ever exist. 

Just because your writing isn’t
popular doesn’t mean you are a bad writer. Don’t ever compromise who
you are, who your characters are, your plot, your writing style,
anything for the sake of readership.

There are popular writers everywhere.
But there are only so many good writers.

This is generally true, but I think what it misses is that popular writing usually does manage to do one thing well, and that’s scratch the biggest itch for the largest number of people.

it can be good popular writing or bad popular writing that does this. but that’s what it does – it gives a large mass of the fandom what they want, and what they want may not be what you want. Most of the fandom may want domestic curtainfic fluff for the juggernaut. You may want angst and pain for the juggernaut while your favorite rarepair solves a mystery. Most of the fandom may want seven million iterations on the time the heroine Chose The Wrong Man. You may want adventurous humorfic between the heroine and her best friend. Popular taste isn’t necessarily bad – sometimes it’s very good! – but sometimes as a fanfic writer, the thing you want to write may not line up with that popular taste. 

This is fine. You can write to be the most popualr, but if you do this you may not be writing what you want to write, so at the end of the day the central question you ask has to be: did this fic give me what I want to see? regardless of how many kudos or comments I got, does this scratch my fandom itch? If it did, then I would say your fic is a success. because it’s for you. 

whether it’s good writing or not is an entirely separate question, but I think that when you look at your writing, it’s a lot easier to be pleased with it and to feel like you executed it well if it’s giving you what you want to read. whereas if you are slogging along writing only what you think other people want to see, it becomes harder, I think, to muster up the passion to care about getting the characters, plot, setting, or style right. 

Luck also plays a huge role, especially in big/active fandoms. It takes the “loudmouth” readers who are willing to comment and engage and tell their friends–who are then willing to comment and engage and tell their friends–and on and on. You could be a fantastic writer with a fic all of fandom would love, but if people aren’t engaging with it, the fic gets quickly buried under other content and is lost.

Unfortunately all you can really do is keep posting and hope the loudmouths find you.