A little abrupt, don't you think? She was just asking why you thought her vet was an idiot. Just like everything else in horses, there are ten different answers for one question.
I'm not sure why your horse is losing so much weight. But I would seek out different opinions. Sorry I'm not much help.
The vet is an idiot bc:
"My horse is on sweet feed." My horse has ulcers." My horse is losing a lot of weight." "My vet doesn't know whats wrong."
Really? First of all, no GOOD equine vet would agree with feeding sweet feed or any high NSC diet to a horse with ulcers. A GOOD equine vet would know that hay/forage would need to be provided MUCH more often, free choice if possible. A GOOD equine vet would prescribe an actual medication that would HEAL the ulcers. Ranitidine and Ulcerguard are the only two medications proven to HEAL ulcers that I am aware of.
OP, Good luck with your horse. I'm sure you will get her back on track if you follow the suggested info. I just rehabbed a severely starved TB mare this fall who also had sever ulcers. The new owner (I rescued her, but I couldn't keep her. I started rehab on her and found her a good, forever home) just emailed me videos and pics of her a couple weeks ago. She followed the feeding/medication plan I had set for the mare and she looks GREAT!!! Completely recovered.
I would be more than happy to give you my rehab plan if youd like to start there for your horse.