Dozens of industries rely on animal byproducts in order to be successful. To a lesser extent, plastics we rely on require long dead animals in order to be produced.

How could we realistically colonize space to a level of industry that we have in modern times when the availability of both animals and fossil fuels would be drastically reduced if not gone altogether? (ex. while irrelevant in the context of greater humanity, anything requiring whale byproducts can say bye to their products)

I feel like there's so much focus on getting into space itself and literally zero thought beyond it. We want to put someone on Mars why? Why not resolve other issues to make living on Earth more efficient and make humans more self sustaining first before jumping to these lofty fantasy goals?