But seriously, there are many reason given for being one of the many forms of 'vegatrianism.'
Some are religious or psuedo-religious. Harming another living thing and such as this.
Some are health reasons. Some of these are based on facts. Most are based on fantasy.
Some reason are political. (see PETA and such groups)
In my personal perspective vegatarianism is unhealthful and quickly becomes a psychological crutch. Even the most carefully constructed veggie diet under the best of condidtions will not supply essential nutrients to the human body. Supplementation is needed to make up for this short-coming.
Having said that I will admit that prior to going on the ATKINS plan, I ate very ltttle red meat. I also maintained my cholesterol under 200. Since going on ATKINS, my cholesterol has dropped to 156 and my good cholesterol has increased and bad cholesterol has dropped.
All statements are purely my own opinion.