Art, like beauty, is in the eye of the beholder. If it's art in your mind, it's art. Trying to convince others something is 'art' is missing the point completely. For me, Silent Hill 2 is high art that works on multitudinous levels, creating the pre-eminent gaming-art masterpiece, singe-handedly proving beyond doubt that games can work on the same level as books films music. To the next guy it's a janky piece of *&@£. The world seems to have forgotten that personal opinion is ALL that matters in entertainment / leisure pursuits.
I think what you say is true for people in their adulthood who have already experienced much of life and much of art (in the broadest sense). But you can't deny that something being considered art is (or should be) only subjective. Art is supposed to provoke, too, and therefore it sometimes also provokes discussion whether it even is or should be considered art.
Is Lady Gaga's music art or just pop music, is the persona "Lady Gaga" art reflecting on pop music? To even be able to start such a discussion makes it an art form – even if I don't necessarily "like" the concept of Lady Gaga etc.