By your admission you don't own any machine guns. I do. So let those of us with actual experience determine whether it's worth shooting them, or not. Speaking for myself, I'm 78 years old, long retired, and I don't feel good about burning bundles of cash. The guns, yes; the ammo, no.
No, I don't, but if I did, I'd find a way to go out and shoot it once in a while. Even if it was just a couple mags at a time. I'd curb my other hobbies.
So... Mr Experience, that begs me to ask this question... Why bother owning something you can't afford to use? If it bothers you so much to shoot it due to the cost of ammo, you don't fit into the aforementioned "more money than brains" category, so what category ARE you in?
Are you one of the few who bought it as an investment? Did you just buy it for the cool factor? I don't get it? I understand "more money than brains"... seen lots of them, I don't understand "less money and even less brains"... or whatever would cause somebody to spend that kind of money on something... and then be afraid to use it... Where is the joy of ownership, if it can't do, what it was designed to do?
Why drive a powerful car, if you don't take it to the track every so often?
Why marry the woman you love, and not take her out dancing?
Why have a dog, and not go out and throw the ball with her?
Why have a machine gun, and not shoot it?