Well, that assumes other lifeforms are drastically ahead of us in terms of their technology, whereas it's possible other lifeforms are further behind, or only marginally ahead of us. That could explain why they've never come here.
There's a theory out there that most lifeforms evolve to a point where they destroy themselves. I suppose it's largely borne out of how humans have treated the Earth. Yes, we've progressed in technology, but we've arguably damaged the Earth with pollution leading to climate change, etc. Obviously if things get worse, we could see Earth becoming uninhabitable before we develop the technology to leave.
The same could apply to other lifeforms - ie they've progressed to a point but have wiped themselves out before developing long distance space travel.
