Collectively we like to think we are an intelligent species. But for all we know the planet we’re riding on is a galactic short bus. We’re just a tantrum away from global nuclear war, and if that doesn’t happen, our ongoing collective effort to make the Earth uninhabitable will be the end of us.
When and if aliens show up in a meaningful way, we may find out that their Prime Directive is “Destroy all competition.” But they might not do anything so wasteful and expensive as firing a shot at us. They may think that any species that can develop thermonuclear weapons and also put maniacs and lunatics like Pol Pot, Stalin, the Kim family, Hitler, Mussolini, Trump, Ceaușescu, Mao, Amin, and Saddam Hussein in charge of people, all in one century, are pretty damn stupid and self-destructive. They only have to wait another century and humans will be gone, but the metals, minerals, and water will remain – free for the taking. So we might not see the aliens, they might not show themselves. They will just leave a few (probably automated) observers and resource locators hanging around so that they will know when we have finished killing ourselves, and where best to dig.
Help Us? Why bother?