Isn't there a point beyond which doing more IVF is just a bit... sad and desperate?

Well, I wouldn't have worded it like that, but yes, there is. There is a point for every infertile couple beyond which it's just not worth continuing. That point varies widely between individual cases and depends on a variety of factors. The only people aquainted with enough of these factors to make a decision on the matter are the couple themselves - not their friends, or family, or even (in most cases) their medical specialists. It would be best not to offer an opinion unless asked.