So, who do you believe does more damage to the environment on a yearly basis:
A) All mega breweries worldwide put together.
B.) All homebrewers worldwide put together.
You're not wasting your time, I guess you're just seeing it from a different perspective.
As to your question, on an absolute basis, A). On a unit basis (per L, per capita), B).
Think of it this way. Say there are 100,000,000 beer drinkers worldwide and HB'ers were 1% of that. Say we've brought environmental impact down to a common denominator, where impact per Major is 1 unit and impact per HB'er is 5 units. So the environmental impact is:
100,000,000 "megaswill" drinkers x 1 unit = 100,000,000
1,000,000 HB'ers x 5 units = 5,000,000
Net impact = 105,000,000 units
Now if everyone was a megaswill drinker, the impact would be:
101,000,000 megaswill drinkers x 1 unit = 101,000,000 units
If everyone was a HB'er, the impact would be:
101,000,000 HB'ers x 5 units = 505,000,000 units
Regardless of what type of beer you drink (megaswill vs HB), you'll still drink it. There are still the same number of people drinking in total. If they all brewed HB there would be a greater environmental impact; it comes back to economy of scale and efficiency.
HOWEVER, we don't brew our own beer to be environmentally friendly, we brew our own beer because we enjoy the experience and the vast array of styles we can brew. And there's nothing wrong with that... just don't be mistaken that it is environmentally the better option.