Also I have found that people who think that their low class horses are middle class and middle class horses are upper level horses have a hard time moving forward and improving.
Very true. For me its quite the opposite. I don't push my horses hard enough
Most people have middle class horses. Maybe she means middle class as middle quality? Very few have high class horses, because the market dictates they are more valuable. And well lets face it, most horse owners arent made of money.
If you have a somewhat decent horse, who performs well, I would consider them middle class. For PSG horses I would consider them above middle class, because they are great performers, and above average. Low class horses are going to have alot of defaults and training issues. I think some horses can raise classes depending on the training, but some never can. My mare will never be high class, she's got some good lines in her papers, but she's got navicular and is unridable. My qh is definitely middle class, to low class. He's got almost no training, and was dirt cheep. He will hopefully rise to middle class/middle quality once he's got professional training.