> Doing it is evil and makes you evil.
Whoa: hold on just a second there. I don't necessarily disagree with your wider point but we need to step away from this inflammatory and accusatory language.
You said that you used to guilt-trip people constantly when you were younger, and then you stopped when you realised how sick it was. Doing it didn't make you evil: it made you immature, and then you grew out of it.
Except that - and I sort of hate that I'm pointing this out - you haven't entirely grown out of it because you recommend people not do it but then brand them evil if they do. That's guilt-tripping, and it's manipulative and inflammatory. (Still, we all have our off days and revert to type from time to time, so please don't see this as a personal attack.)
Anyway, my wider point is this: part of maturing is developing better and more effective social skills. Hence many people change a lot between their late teens and mid-20s.
Not everybody does though. If guilt-tripping and similar kinds of manipulative behaviour become the pattern someone follows throughout their life (i.e., they don't choose to grow out of these behaviours) that might make them evil, but let's try to avoid almost literally demonizing vast numbers of people who are probably just immature.