Fwiw, I don't think what your co-worker is doing is a big deal and in my experience, I agree with the idea that almost everyone takes stuff from their work in one way or another. I also agree with what he says about the company not missing the money - it simply won't if it's just one person doing this stuff occasionally. When I previously worked as a barman, we swiped drinks from time to time. At one place (the other was far tighter on this but soft drinks were still fine), if someone ordered a drink and left without paying for it, it was ours as long as we drank reponsibly. When I worked in a music store, if you needed new guitar strings or picks you just took them. In our lab, I use some of our reagents for myself - 100% ethanol is a brilliant computer screen cleaner. Strictly speaking, if the lab paid for it and it's not being used for research, it's theft. But we all do it because we can, my supervisor included. When you've got access to nice things through your work, go ahead and take them if it's not gonna be a big deal - which in many cases, it isn't.
It's good of you to not report him, by the way. Morally, okay, he probably shouldn't be stealing but as I say I can't see it as a big deal and it's really not something worth losing someone their income and potentially damaging their employability in the future over. Way I see it, no-one's getting hurt, it's costing the company an impossibly insignificant amount next to the total that they probably take, and it's not one of those things that it's worth getting bothered over. There are probably far bigger injustices going on "higher up" in the company or elsewhere than a drink getting swiped occasionally.