At the very least if it is to be of immediate use, looking at space might one day alert us of dangers from space. Any potential dangers such as large meteorite impacts have remained relatively un-noticed for the last several million years, and probably won't be a serious threat for a very long time to come. More generally, there are a lot of different sides to astronomy. Because of this there are a lot of different reasons why people like to get involved. As already stated, amateur observers can make a significant difference.
Some people enjoy the technical side of looking at space.
This might involve recording data, calculating figures, and being rewarded with the satisfaction that they were correct. It might not even involve going outside. Other people enjoy a more active approach. This could mean taking really great looking photographs, submitting observations, or simply scanning the sky for new phenomenon. Another sector of people just like lying back, looking up, enjoying the night air with it's mosaic of stars, and wondering.