I knew a neighbor kid while I was growing up whose dad always hammered him about wanting to take up Radio Controlled model aircraft...The dad though it was a stupidly expensive and pointless activity...He would shout at him with a really angry voice, "What is this going to get you in real life?...You can't make a career of it!"
John Lennon's grandmother, well-meaning though she was, once told him, "The guitar's all very well, John, but you'll never make a living at it."