Up until recently, fear of failure. It's still there, like when I got to the 13th most popular community novel last week, but have dropped back into the 125 position at the moment I'm writing this reply hahahahaha.
It feels disheartening to feel like you've failed like that. I know it's something that happens and I'm doing well on other platforms, but still, it stings quite a bit to have that happen.
But I keep going. Mostly to feel good about writing and all, but also in the hopes I can turn what I love doing into a source of income. You just gotta keep going one step at a time I guess hahahahahaha