People choose to be vegan for health, environmental, and/or ethical reasons. For example, some vegans feel that one promotes the meat industry by consuming eggs and dairy products. That is, once dairy cows or egg-laying chickens are too old to be productive, they are often sold as meat; and since male calves do not produce milk, they usually are raised for veal or other products. Some people avoid these items because of conditions associated with their production.
Many vegans choose this lifestyle to promote a more humane and caring world. They know they are not perfect, but believe they have a responsibility to try to do their best, while not being judgmental of others.