It makes sense if you're never planning on selling the plane. My Skywagon for example, it was one I could (barely) afford so it's not perfect, but it flies and is mechanically sound. I'm going to have to put ~50k into it for paint, interior and panel. Not to mention a new engine and prop at some point, but to me it's worth it. I'll have a plane that is truly "mine" by the end of all of the upgrades. Of course I'd never make my money back if I sold the plane... but I certainly don't plan on doing that ever.