Profit drives the agribusiness, not concern for the animals', the workers', or the public's well being. Workers suffer too. Massive institutionalized violence in the slaughterhouse no doubt has psychological effects on workers as well. Diseased food, massive pollution, and inefficient use of resources affect everyone. To stop the suffering of animals and to truly respect them requires us to stop exploiting them in the use of food, clothing, and entertainment.
Vegans are individuals who strive to do no harm towards animals.
This means that they try not to use, eat, or wear any animal products such as meat, eggs, dairy, wool or leather. Few individuals can make this drastic of a lifestyle change overnight, so many start off giving up meat first, then eggs, then dairy, etc. It is important to remember that it is better to change your lifestyle a little bit than not at all.