The first is certainly valid reasoning in Go, and I phrased it in a way that should make that obvious. But you can also phrase it as "I've spent so much effort trying to reach goal X that I'm committed now", which is almost never sound in real life.

For the second, I'm not thinking so much of tewari as a fairly common kind of comment in professional game commentaries. I think there's an implicit "and I surely haven't made a mistake as disastrous as a two point loss" in there.

It's probably still not sound reasoning, but for most players the best strategy for finding good moves relies more on 'feel' and a bag of heuristics than on reasoning. I'm not sure I'd count that as a way that Go differs from real life, though.