Arghh I'm so mad! does anyone agree with me on this?

I know exactly what you're talking about because I've seen it happen too many times and it's always very sad. There isn't much you can do unfortunately without really offending her. The only thing you could do would be to try and help her improve her riding subtly but otherwise you can't do much. It's very unfortunate that she keeps buying such high quality sports horses if she hasn't got the riding skills, maybe she can't even see what you're observing. So perhaps subtle tips on riding improvements wouldn't go a miss.