Well as to my experience, you must have goals for your story, like, how would you want your MC to grow? Or what do you want to show to your readers?
If you know the answers to these questions, then you can always disregard the drops, or the 'preachy' readers. Another benefit is that, when you know the goal or the direction of your story, there is the less chance of your work going out of focus.
Another suggestion I could give you is to get a 'writing buddy' for an honest, first draft comment on your work. As for me, I got my brother
@Chisystiks do that for me. But this is just an option.
Take note, the emotional effect of seeing others drop your work is still there, but at least, the pain is minimized.
Oh yeah, and remember, when you feel like quitting, the more you should stick to your work.
Edit: I also want to add that, not all readers would like your work. Things like demographics and cultural values also come into play when it comes to preferences. I know it's basic author knowledge, but see, when you think about it the moment you see someone drop your work, the effect is lessened.