Not, of course, that skills maintenance is the only reason to keep in practice. As an example, the need to become a better trumpet player that spurs Phil on to keep tootling away and making poor Elly's life miserable. Unlike his stupid, lazy older sister and her belief that once she learns something, she doesn't need to improve herself, Phil is in competition with the man he was yesterday and he doesn't want to lose to that guy. He's got way too much pride in himself to ever let that happen. Since Elly doesn't and can't understand that because she has no pride in herself and simply wants to throw her hands up in despair and yell about unfairness when the going gets rough, she ascribes his need to succeed to wanting to torment her.
That being said, the crippling self-hatred and fear of failure that makes her moan about how people expect too much of her is not the only reason that practice makes her feel persecuted. We also have to remember there's a defiant six year old kid inside her that resents being told what to do. When we combine a stubborn hatred of being told that she has to do things that are boring and hard like everyone else with a fear that she can never actually do so, we end up with a poor student who drifted through her life thinking that once she'd managed to do her evil teachers the favor of pretending that she cared about their boring mush, she could stop learning things. To her, Phil's incessant playing of bees and bops and encouraging Mike to follow his path means that learning just keeps goes on and on and that's just not faaaaaaaaaaaaair!!!! Fortunately for her, though, she growled and berated and threatened and demeaned her way into getting the scales to balance and now Michael has the right attitude: things that take effort to accomplish are worthless because one has to endure pain at some point in the process. Better to be happy and never do anything.
What this all means is that as I type this, she's probably howling in anger because the April of 2013 has the evil, selfish habit of not listening to sensible people like Eva Warzone and Uncle Hayseed McTurniptruck out at Exile Farm who tell the child what she needs to hear, she listens to awful people like Phil who tell her crazy things about how she should have enough pride in herself to not settle for mediocrity and suburban ennui.