Why do people eat meat?

Because it is tasty and good! And advertisements rules the world!

Do people realize that they are eating an animal?

Not exactly, because meat on their plate is considered as a product in first place.

When will they realize that this is not a product, but part of a living creature?

I always say, a story has two sides, like every coin. Advertisements only show the "good" side.
So that's what I did... I went to look for the other side. Result: no more meat for me, because I do not have a reason anymore to eat it.
It is all manipulated and this Sir explains it all well!