In the context of this thread, it means one thinks they got lucky and the work they produce doesn't qualify to deserve that much recognition.
I had faced a similar situation. Around five-six years ago, I had published a story on Quotev and it grew popular. I didn't even understand why. My writing was absolute garbage. My friend, on the other hand, is a literary genius and when she published her work, I was certain it would blow up but no. It still has hardly 2-3 likes.
I felt like I was cheating. Didn't deserve it. But I didn't dwell on it either. Since I felt like I was a cheater, it drove me to improve to the extent that would make me more comfortable talking about my work around her.
Long story short: Dwelling on impostor syndrome is not productive at all.
Instead of the "who is fooling who", it's more about the progress and the improvement as time goes by. The former is beyond your control, those "fools" that you think of are checking out your work because it's their choice, the time and place was right or they actually enjoy it and you don't realise it, but focussing on the latter will save you from the over-achieving mindset and the depression that might follow the second time you try things and it doesn't work out. When you start believing that it's alright if your work sucks now and that it's NORMAL to improve from a failure to a decent artist, it becomes way easier.
Just focus on improvement.