"I just paint for myself," or other variations are commonly used in an attempt to deflect critique. I don't believe most artists who use this line truly subscribe to only creating for one's self.
If they do, then it's an even bigger problem than just not wanting to deal with scrutiny. No matter how original, we owe our peers and the generations before us an immeasurable amount in the formation of our skills and Ideas. It would be incredibly selfish to take what we've gleaned from others and hoard it, no matter the level of deftness.
I want to pay what I know forward; I see the dissemination of my paintings as a way to give back and reiterate the knowledge collected. Many people stand as examples and inspiration to my career. I wish to honor them by adding upon and growing the branches of the art family tree.
I am not saying people must share every sketch or doodle, or that they must try to achieve worldwide recognition. An artist's most frustrating and seemingly unsuccessful work informs and helps strengthen the more pleasing accomplished ones. If you're still worried about mean spirited comments, begin sharing with close friends and family who want to help you grow, then consider more public avenues.