[pingou]

"Furthermore, vegetarianism, though morally laudable, has an obvious economic limitation — when one person refuses to eat meat, it lowers the price of meat for everyone else"

I very much doubt that, I think the opposite is happening in the long term because of economies of scale.

So go ahead, become vegan! You already know you should!

[veltas]

Lowering demand doesn't always lower price. Assuming the industry is competitive, and capable of supplying all demand, which it usually is, the loss of demand mostly means less money for the producer, and more money for the former consumer to spend on something else.