If you are sharing your idea, try to divorce your idea from your ego, when listening to feedback.
When someone is all excited and starts explaining to you their idea, don't immediately reply, 'but, there's an app does that already'
Carefully listen to the idea completely, before giving feedback in between.
Make a mental note about the points you'd like to raise when the person is done. Think for 5 minutes on those ideas yourself. And then give your feedback
Ideas are powerful, but delicate. Be gentle.