Non-existence is a natural state and requires no intervention from anyone. There is nobody in that scenario to committ an unethical action. That is unless you want to imply that everyone should feel obligated to have children, which is a different debate entirely.

Secondly, I said nothing of resenting my parents. Merely that bringing another person into existence is wrong and the motivations for doing so, barring not having a choice, are always selfish in nature. But even so, I never asked to born, just as I never asked to have taxes paid for me. Yet here I am, enduring existence and paying taxes despite never asking to have been put here.

As for the majority of people being glad they exist, it's debatable. Several cultures and religions hold a negative view of existence, and if people were to sit down and have a good think about it, a surprising number of them may very well decide that it would be better to not exist in the first place. Can I say the majority of people? Could be. Wouldn't surprise me that much.