Whether lay-Buddhists should be vegetarians or not have been debated for ages.
For the monastic’s (monks and nuns), the Buddha laid down a precept in the Vinaya (1) saying meat (2) can only be accepted if they know the animal hasn’t been specifically killed for them. Other than this they need to accept whatever is offered, but they are free to decide what of it to eat.
For the laypeople the Buddha didn’t lay down any precept regarding vegetarianism, but he lay down a precept saying not to kill any living beings (3).
The majority of the lay-Buddhists are non-vegetarian. Since the monastic’s can eat meat the laypeople allow themselves to buy and eat meat, as they don’t consider the animals which the meat comes from, to have been slaughtered for them directly.
To me this sounds strange. Buying meat creates a higher demand and causes more slaughtering of animals thus it indirectly breaks the first precept, and “it’s ok as long as others kill” is indeed selfish.
As Buddhists and humans we are free to do what we want to, but we should be honest with our self and others regarding what precepts we are having difficulties in following and not make any bad excuses.
1) Discipline for the monastic community, 227 precepts for the monks and 311 for the nuns.
2) Meat also include fish.
3) Humans, animals and insects.