We will have unlimited robotic labor by the time we are doing stuff like this so there is no need to worry about those issues. You will have so much cheap production that everything will be dirt cheap and people will be bored enough to try crazy space exploration ideas.

Humans might tear themselves apart, but you won't really have production and resource problems AND a lot of these ideas don't compete against domestic improvement anyway so you will be doing both constantly like now.. just at a much faster rate.

Plus there are few single inventions that would benefit humans more than the ability to transfer a human mind into a machine because that opens up all kinds of new doors so you would want to do that even if you didn't care about space travel and you want the robots to automate your production as much as possible.. so you're already building everything you need for space travel for domestic uses anyway.. there is no real loss there just more reasons to do the same thing.