Yeah, kinda doubt explorers do their thing because they wanted a back up just because home might fail?
Exploration is just adventurous and fun. IMHO, it’s also better to develop new technologies to explore rather than for war...
Of course we could save all the money on such research and development and use the money to feed the poor..., but you’d probably get better return using the money to feed the designers and builders of these exploration vehicles... of course Mars doesn’t have to be it. Universe offers us endless possibilities...