Should we be spending billions on space exploration or use it to transform human lives here on Earth/Gaea?

It's not totally an either/or binary question. A good portion of the space research efforts are at better understanding how and why our planet and climate is changing. The biggest payoff from the original space program was not planting a flag on the moon or drinking Tang, but the tremendous leap forward in technology, computer development, miniaturizing of technology, development of solar panel power systems, etc., that the goal of a man on the moon by the end of the decade required.