I think we are talking two different things. Water vapor existing because of water is not the REASON for its existence. Water is essential for water vapor to exist, it's a requirement not a reason. Why does water vapor exist in itself? Water, when boiled turns into water vapor, but that's the mechanism, not a reason. I punch Harry with my fist. My flexing of muscle and exerting force is the mechanism of my punch, not the reason of my punch. The reason I punch him is because I am angry at him. I can't point to a similar reason for water vapor existence.
Let's get over the semantics now as this is not a discussion about grammar and intent, but about religion and everything else.
You said you were expecting a deeper level of answer why is evolution happening. Maybe you are looking for the answer that suits you, would you consider an answer out of that paradigm? When you ask what is the ultimate goal of evolution, you are automatically assuming that there IS an ultimate goal. Why is that assumption necessary? My reasoning doesn't rely on any assumption; there are things without "ultimate goal." Why does Jupiter have Europa as its moon? I can tell you how it got Europa but I can't tell you why and I won't believe if somebody tells me they know why. If you claim that everything has to have a reason, then I resort to the question that made me agnostic; the question that Rethink has asked as well, why does God exist? Who made God? If you say, God made God, then I will say universe made universe. That answer just doesn't jive with my logic.