Why do so many men think that being Vegetarian or Vegan, is 'unmanly'?

Because they have fragile masculinity.

Because it kinda is.    

Is that truth or just opinion?

If so, possibly

PROTEIN!!!!

Look it up.

Guys still grill Veggie or Turkey Burgers, DAMN, in Wisconsin, we have Corn on the cob grills, I think it has to do with genetics and what the body craves.

One of my best friends cooks up Vegan stuff cause his girlfriend is.

Meat just tastes good.

There are men who are "MEN", but don't like fish (???).

I think you're blowing this out of proportion?

People eat what they like, what they're used to, and, at times what their body craves of depleted nurishment.

It's as camp as a row of tents.

It is the MAN/MEAT mentality-which shows merely being naieve.

For the same reason they like big dogs, macho type motorbikes and cars, etc. It makes them feel "tough" somehow.

Personally, I feel perfectly adequate without such things - but to each his own.

It's because being vegetarian or vegan is unmanly. An alpha male doesn't want to be a soy boy. I'm also an alpha male.

I don't think that being vegetarian or vegan is unmanly.

It's just it's just inconvenient as all heck.  I have to work to support my family and to pay bills I don't have time to set around and cook green vegetables and peel fruit.

We get 30 minutes for lunch that's barely enough time to eat a sandwich with a piece of meat in the middle and a piece of cheese and a tomato and some lettuce.

It's much more convenient to let animals eat the vegetables and then we eat the animals that's just the way it works.  It is apparent by looking at people's teeth that we are not vegans or vegetarians were omnivores.

Perhaps one day they will develop vegan meal bars that actually taste good where when it comes time to eat we can all eat our Soylent Green drink glass of water and go back to work.

Because a lot of men enjoy sinking their teeth into a big slab of red meat.

For the most part, over the long course of human history, men hunted and women gathered and prepared food.  With agriculture that's no longer required but we have quite a lot of momentum (agriculture is a relatively modern invention for us humans).  Some people don't like change and others can't even consider it.  But we humans are good at adapting to changing conditions and we'll figure it out eventually.