The simple argument against veganism: by providing animal husbandry we can give animals a good life, in exchange for their produce. This is a win-win for humanity and the animal.
In practice the vegans are correct about the horrors of factory farming.
But they synthesise the wrong principles from it (that humans are bad for consuming).
Factory farming comes not out of capitalist greed, but a bad moral foundation. Humanity needs to learn to treat itself better before we can treat animals better.