I can't imagine the very best riders have ordinary day jobs like the rest of use. I'm sure some of the very best showjumpers, for example, can earn a fair ammount of money from sponsors and competitions.
The prize money is generally not enormous, not enough to make a living on. Professional riders generally have sponsors which purchase the horses they ride and their gear. As an income, usually they coach and train, for a lot more than $50/hour! Also breeding top competition horses, conducting clinics etc.
There are some though, that still have 'norma' jobs. I know of a few Olympic dressage riders that practice as veterinarians and dentists ;)
My trainer doesnt have a normal job but she has major sponsores naf for example and winning 150 - 200k is pretty decent and will sort you out for a while like I said lessons vary prices the more they compete the more money you have
Depends on who you're talking about. A lot of the top showjumpers are at shows pretty much year round and rarely at home so no, can't have a "normal" job. Their income will come from different places depending on the rider.
For example... Beezie and John Madden own a farm in NY but are on the road about 95% of the year. She's sponsored by Ariat, Charles Owens, Delgrange, Purina etc. So Ariat gives her clothes and pays her (and john) a little per month, Purina provides feed, Delgrange gives her saddles when needed, etc. Believe it or not, but most sponsorships don't pay a lot of money, they just equip their riders and pay a little. John does mainly buying/selling/importing, occasionally evaluates horses, and coaches a few students on the side. They have a few horses in training but their assistant rider Callie does most of those rides. They do a little breeding but not a ton. Beezie wins a boatlaod of prize money. John told me that the vast majority of their paycheck comes from buying/selling horses and prize money. Their major investor Abigal Wexner owns most of their horses and thus pays most of the expenses.
McLain Ward on the other hand has the same rigorous show schedule, but also teaches clinics on the side, which the Madden's don't really do. While he might buy and sell some he it's not a focus of his like John.
There are others who are just independently wealthy. Now wouldn't that be nice....