Should the remaining survivors of the 12 colonies have searched for Earth?

I just finished BSG and I'm beating myself up to have waited so frakking long to see it. I love Colonel Tigh a lot so I'm going to use frak a lot.

One of BSG's premise is to save the human race from extinction. It may seem stupid, even cold and callous but why does it matter that the human race survives? I can understand families wanting the family line to go on, but when someone says that the human race must survive, why? Apart from survival instinct, why do we give a frak so much?

Anyways, based on the book of Pythia a dying woman will lead what's left of the human race to Earth.

Now, before they arrived on Earth none of Galactica crew knew that the 13th colony was in fact the Cylon race. They believed they were humans and that it was a place they could call a sanctuary and perhaps save the human race.

And that's exactly what I don't get.. based on the prophecy the human race is perhaps thriving. Why shouldn't they have gone looking for Earth? The most obvious reason being the frakking Cylons were on their frakking tails.

From Kobol to Caprica to New Caprica, to the Nebula and the Cylons kept going after them. That is literally leading the enemy to their new found home.

So had the 13th colony being in fact humans, and that the human population on Earth were not on the brink of extinction, what is stopping the 1st and the others from wiping out the human race altogether?

So yes, what I'm suggesting they should have done was to lose the Cylons if possible, find a habitable planet and just try to survive there. If the Cylons found them, well they're simply frakked. But at they least they can die in the belief that somewhere the human race is thriving.

Of course had they done that, there would be no story. But in essence that's what happened in the finale anyway - there is nothing stopping the Cylons that were freed to return and wipe the human race out of existence.

Tl;dr Was it right for the survivors of the 12 colonies to have searched for Earth and thus putting a hypothetical 13th colony at risk of extinction? Or am I and this question just frakked up?