Honestly, I have my serious, serious doubts that man will ever inhabit a planet besides Earth. I don't think we were meant to live anywhere else. I also don't believe the human race will go on forever. At some point, everything comes to an end. Whether it's a quick process, or goes on slowly over time, it's almost inevitable.
The people that were living thousands of years ago never would've dreamed that man would someday walk on a planet not our own. We've advanced so far from what we were years ago. That being said, I don't think it's a necessary waste of time or government funding. I'd rather the government be spending money on something useful that some stupid idea some yoo-hoo in a high seat came up with.
I don't think it should go unexplored. I don't think that mankind should hold off on learning about things not of "us", so to speak, if we have the ability to explore and expand our knowledge of our surroundings. I also think that we should focus on our oceans, and see if they can't help us out any.
We've got the means, we've got the intelligence. I say we put it to work, but with the right mindset.