You forgot to "therefore" your metaphysical presupposition of naturalism on rye with a side of ad hominem.
Allow me to clarify your reasoning, such as it is:
1. Naturalism is necessarily true.
2. Abiogenesis is necessarily possible.
3. Life necessarily arose on Earth via some process of chemical evolution.
4. There are gobs and gobs of stars.
5. Therefore, life necessarily exists elsewhere.
It would seem that your conclusion is necessarily embedded in a number of key premises that are indemonstrable assumptions.
Just saying.