Before four billion years ago, Earth was too hot. Life on Earth had to have a beginning. Life in general life in the universe is another, and a quite different, question. If the question that scientists pose for themselves is simply too difficult, they are limited to pure conjecture. For example, in the Middle Ages, how Earth was formed was a question scientists could only guess about.
Science can only make progress by taking small steps.
If we figure out that one, we probably deserve a vacation before we tackle the next problem. Yet many scientists continue to assert that the question is how life began in the first place . They say that knowing life on Earth comes from space would be of only minor interest because it sheds no light on the question. With that attitude, it is fruitful to ask more and more precise questions. Even if we never find out how life begins in the first place, it makes a lot of difference where life on Earth comes from.