In regards to vegans, it really, in my opinion, depends on their "ideological" viewpoint. If someone's veganism can be explained as an unwillingness to participate in the food industry of today, I can see it as a valid and reasonable effort.
Nonetheless, if their motive is that we as people shouldn't use animals as food at all? Because we don't need them as a part of our diet. Well, there's a compelling utilitarian argument against this approach in my view.
Most of the animals we use for meat, dairy and other food, wouldn't be alive/exist at all when there wouldn't be the industry in the first place.
Life and death are one. Therefore, when anything is alive, it will inevitably die one day. So concern about the death of these animals is just nonsense. Even the happiest lives will suffer from death. Happenings between the birth and the last breath are what should we be concerned with.
If we as species will be able to change the way how we handle our meat, dairy etc. production one day. When animals will be raised in a different way than now, not on the industrial scale without any sense of compassion. Let's say, a cow will live a few years with their calves, will have a possibility to move freely etc. (like some "bio" farm already do it). Something along these lines. Then to raise animals for meat will mean a few years of existence, rather than non-existence and as such, I view this as more beneficial for "both parties".