Earlier quoted context omitted.
There's a difference between being frugal and being an asshole. If you have enough money that tips are a rounding error for you -- not tipping just makes you an asshole.
It's none of your business to ever tip anywhere UNLESS you explicitly want to thank somebody for their service. How hard is that to understand? It is the workplace's responsibility to pay their staff adequately. NOT YOURS. 0% tip all the way everywhere. No matter if I have $10 or $10k on the bill.
That's exactly the point? Buying iced tea everyday for some time means that he liked it. Not showing appreciation to something he clearly appreciates