But seriously, only when all our eggs are in the same basket do we risk extinction. It will happen eventually unless we can colonize another world.
Short-sighted solution. The sun will only last as a blast furnace about 4 1/2 billion more years, and will become quite unpleasant for us long before that. Besides, the sun could get clobbered by another sun most any millenia now. It's always problems with the furnace when it comes to real estate.