It's that feeling that creeps out of the shadows, sneaks up behind you, latches onto your creative jugular and rips you to shreds.
I am not as great an artist as they are.
When you are doing art to impress people, to become Internet famous, to be the next big thing; when you stop making art for yourself and only for others, that is when you put aside what makes you different as an artist. The moment you compare your work to someone of an equal, lesser, or greater experience level is when you've unconsciously blocked your ability for originality. Own your style, experiment with different ways of putting lines, shapes, and designs on paper/computer; but make them your own. If everyone's work looked the same it wouldn't be art.