I want to excersize race horses when I get old enough...questions?

Ok I really really want to excersize race horses when I get old enough. Are the horses really freakish? I learned to ride on off the track thoroughbreds, so I know that they can be psyco, but are they alll really nutty when you try to excersize them? I watched videos of this one guy where the horse reared constantly for 10 minutes before he could even make him walk. i'm not scared of it, but I was just wondering. Also, is it more dangerous then doing eventing/jumping? Thanks in advance.