I sorta agree. Mars is dead. Humanity (for the most part) vastly underappreciates how vital internal heat is to life on Earth... and the lack of the same on Mars will make it a perpetual sinkhole for any energy we invest into it. Nuking the poles won't change that... just give a very brief warm/wet spell. Any colonies on that planet will have to be enclosed and perhaps even sub'martian' for the most part... until we've grown powerful enough as a specie to move it into a lunar orbit around something massing enough to knead its core back into action, akin to galilean moons, perhaps. That said, this is not reason not to go. The path to other stars will need a few steps along the way, and for that Mars is a worthwhile part of the path. 'omg, it's hard' is a terrible excuse.