Heck NO!!!! Oh how I wish I was 30 again. I was still showing at 69yrs and wouldn't have stopped except I didn't have the right horse for it. I now have a new horse and am thinking of getting back into showing at 73 yrs. The joints creak and the knees hurt but I think I can do it, just wish I had a decent place to do some schooling.
Go for it, you certainly won't be the oldest person competing.