How much difference would it make in your life if you cared more, or less, about grammar?

probably not much

If I cared more about my own grammar, it (my grammar) would probably improve. But if I cared more about other people's.....not only would I be an unwanted annoyance, I would also be wasting my time. Brazilian Jiu Jitsu is more beneficial. A grammar Nazi would be completely powerless in ground-fighting. Their grammar would be useless.  It wouldn't be able to save them from being choked-out. 

Grammar...we don't need no stinking grammar.

A considerable one.  It would decrease the comprehension of what is said or written and increase its extension at the same time---resulting in a decrease of precision in communication.

I strive to improve my grammar with great zeal.

Well, I guess if I cared more I would care more. What's really important is faster horses, older whiskey, younger women, and more money.

This is a Randistic Q;))