[xxxdarrenxxx]

This is true.

That said, many inventions in history were not the endgoal, but a side-effect off a research with a different goal in mind.

Do you think if we stopped development on pc's around the 80's, and pick it up fresh in 2017, we would "invent" the Iphone or the SSD within a week?

The internet was mainly motivated for porn distribution, then data, now it literally runs the entire world, and speeds up science and business on a scale that warrants an applause.

We need to walk before we can run, at least that's what I personally like to believe.

Mars is not feasible, but we still can learn many things off (consumer & daily) space travel, and living in a radical different environment by starting with it.

Waiting with any practical/experimental advancement until we are "absolutely sure" more often than not tends to end up in little to no advancement at all, or very slowly.

There are also non-technical reasons to "test drive" inter-planetary migration on a planet that can be "thrown away".

Imagine we find the perfect planet, go there, but then this newly found goverment or terrorists decide to nuke it for reasons. Rather have Mars destroyed, than a super rare planet. Humans like to theorize, but it's accidents and mistakes that drives practical advancement.

[xbmcuser]

If we are able to colonise Mars we would have created technology that would allow us to survive on a fucked up Earth as well so their is little downside in exploring ways colonise Mars.

[xxxdarrenxxx]

A meteor big and fast enough to break up the planet?

It's very presumptumous to say if we can colonise, than we "obviously must have" a solution for this scenario.

Let's fully assume you are right, theory and practise are 2 different things.

Take the burning of the building in London. Convince me it burned down because we didn't have the tech.

The solution and even production for fire-resistant material was available decades ago was it not?

It was inability to come true in practise that made it fail and burned it down. The reason within this context is not relevant. over 100 people dieing was very real, and ctrl-z doesn't work in the real world.

After that accident, buildings all over Europe were revisted and where needed updated with new materials.

A full on destruction off earth most likely will not have this luxury off a revisit, and as such from a survival point of view, it's best to not wait, but just start experimenting with things like space travel and colonies before Hollywood becomes real and a meteor will hit us by the end off the week.