You are right. Who is demanding the supply?
Animals are used in vivisection to find cure for diseases, etc. Most people think that it is justified to use animals for vivisection in our society. The demand is created by 99% of our population that believe this. Everyone on this thread agrees with that it is wrong to inflict unnecessary harm on animals.
Did you know that we have no nutritional need for animal foods. The production of meat, milk, dairy products, honey, leather, eggs all involves exploitation. The animals used for eggs and dairy products are killed when their production declines. Cows, chickens and other animals regularly get their families destroyed. Cow mothers get their babies ripped away from them within the first week of them being born. I went vegan when I realized all of this, since I didn’t want to be a part of paying for animal exploitation.
There will be vivisection of monkeys as long as our society justifies the exploitation of animals for completely frivolous reasons, such as exploiting them for the palate pleasure or convenience of animal foods, despite that we have no nutritional need for animal foods.
Animals are exploited for vivisection, because they are property under law and they are property and resources in our society. If you don't want this to happen - go vegan.