> can you afford it
Now, if all was fine and dandy on Earth and some rich people want to take the risk of starting a Mars colony with the idea that most of us will be able to travel back and forth in a hundred years go for it.
The problem is, there is an asteroid on a collision course with Earth. Oh, and the asteroid was created with help from some of the people trying to now escape. The asteroid is global warming. I can go into great detail on how global warming is going to make things incredibly challenging for the 9+ billion of us around on Earth in 2050. At least to Elon's credit he's doing some things that might make living in a warmer world a little more sustainable before he jets off to Mars. Most people that will be able to pay the price won't be doing so.
Wouldn't be more ethical to focus on saving the one planet most of us and our kids will live on? Lets say the Mars colony is successful. So successful that you and your families chances of surviving are actually better on Mars vs Earth. What gives you and your offspring the right for that greater chance of survival? Because you are rich? What about executive XYZ who lead company ABC for 20 years and used our air and water as a dumping ground for pollution. What gives them the right to leave? What gives them and their offspring the right to survive and thrive on another planet while us on earth deal with the cost of that pollution. As I said, it would be the ultimate FU to 99.9% of us.