Went and read Bostrom's article . . .
If (big if) he is correct, and there is some "great filter" in our future, now at least we have some warning that something nasty this way comes (maybe), and we can possibly take steps to do something about it. Forewarned is forearmed.
There's also the (big) possibility that he's totally wrong and spinning castles in the air, completely out of touch with (the as yet undefined) reality of the universe.
Consider this also - group of people living on an island somewhere, the height of their technology is flint knives. A submarine goes past their island, submerged, silent. They'd never know it was there. There could be a daily parade of submarines, and it would make no difference at all to the islanders - they have no way of detecting them, communicating with them, stopping them, the islanders are beneath the notice of the submarines, or if they are noticed, they are of no interest.
Our flint knives are more advanced (from our perspective), but we may be beneath the notice or of no interest whatsoever to a more advanced civilization - which by definition is more advanced than we are because they have mastered interstellar travel and we have not.
Personally, I'd like to see some evidence of life (current or extinct) on Mars - it would put another nail into the coffin of the creationists.