Going to the New World was also silly for Europeans at the time. Everything was going to be more dangerous, more risky and life threatening. But pushing ourselves to go beyond risk is what makes humans progress in the long run. Going to another planet is a huge, difficult step forward. By all means everyone who goes there will be worse off, but think beyond their existence, 300 years in the future. It may become a pretty nice colony once we figure things out.
I think the analogy is poor, because the "New World" was abundant with resources. The new world of Mars is not, and nearly everything would need to be brought there.
