You make good points on spending, but there is a case for spending on both
There's always a good case for arguing both. All of the arguing and posturing becomes a moot point when you only have a certain amount of cash. It's called competing priorities.
Do you fund Earth activities a little bit more, do you fund Mars activities a little bit more, or do you fund both a tiny bit more ?? Either way, you solve none of them.
His quest is driven by one goal: to ensure humanity becomes a multi-planetary species. This is a good thing.
If that is his only goal then I reckon he was born in the wrong century. I'm unconvinced it is a good thing. I reckon this attached link is closer to the mark.
http://www.youtube.com/watch?v=UOi6v5DD_1M
People were talking about colonising the Moon after the 1969 Apollo missions, and nothing happened.
Bond movies got onto it with their Moonraker episode in 1979....but alas, reality is not the same. Of course, the Moon is infinitely easier than Mars, but we've been unable or unwilling or both.
http://www.youtube.com/watch?v=Z2GTKBx4H5Y
The sun has a finite lifetime. And any number of unforeseen, catastrophic events can occur in the future to--and on--planet earth. It's smart to have a back up.
Yeah, just like the climate science brigade, you're woefully mixing up human scale timeframes with solar body timeframes. They don't match up, never have, never will.
The Sun is about 4.5 Billion years old, and is about half way through it's stable life. It's got another 4 Billion years of stable chugging along before anything dramatic happens to it.
Same can't be said for the Earth however.
Scientists do expect it to expand and get hotter gradually, such that in 1 Billion years time, all of the terrestrial water on earth is vaporised and all life will cease on Earth. No biggy for the Sun. No biggy for the Earth either.
The Earth won't care, and we humans won't be here in a Billion years anyway. No species, especially as complicated as us, has ever survived that long. We're lucky to have scratched out 0.1% of that relatively short 1 Billion year timeframe.
As I said, trying to match up human activity timelines to heavenly body timelines is a non-event.
In any case, the "back-up" theory is defunct. When the Sun eventually goes pop and turns into a red giant, it will expand and swallow up Mercury, Venus and Earth as it expands and consumes everything in it's path, nearly getting out to Mars, so in 4.5 Billion years time whatever is left on Earth will be absorbed into a burning molten Sun.
No need for a "back-up". We won't be here, and neither will the Earth. No need to be depressed or sad, it's just how things will be.