Your office chair is both your saddle and your horse, your keyboard is your low slung Colt and no matter how good you think you are, there is always some young punk who is better.
It is an unfortunate fact that there is an element of jealousy and envy in this game. Some of the worst trolls are other authors and their friends, and there are the back shooters too, just like in the Old West.
Trolling others is not going to make your books more popular, but writing a better book will.
Never respond to a troll, I have said this before, it does more harm than good.
The only defence against falling royalties is to simply keep on writing.
Accept that you are not the best writer and your book is not the greatest work ever penned.
Accept that there is no such thing as a single best writer or a single best book ever penned.
"The moment you go thinking you are the best, that is when that young punk is going to leave you lying in a dusty street at high noon." (said John Grisham of J.K Rowling...probably)