We go to Mars to look foir life and if we find it, it's a failure?

Don't think so. There is a lot of publicly and privately financed research on life past and present Raoul. Extremophiles have relatively high indistrial interest. I doubt very much Martian life will get a ho hum from a funding standpoint. It may well delay or limit human missions, but in the mean time we can use all that technology to explore the Moon and NEOs as well.

The difference IMO is that Mars can carry other programs on its back to some extent while the others can't. Mars is harder to reach on the first try even if it is easier to stay there. Building Mars capable technology will support the other near term targets as well. If it was a huge leap it would make sense to do the others first, but it's not except in terms of time. That time factor is why a Mars mission is a huge step toward a permanant presence rather than flags and footprints.

Regards,
Mark