That's a valid response, and I think it gets at the core of why we do planetary science. There are no military or economic applications of knowing what Martian soil is made out of, or why it lost its atmosphere, or whether life evolved there too. So why do both the US and China fund these missions at all? And does it matter if China returns samples first? First, I would say that in the process of answering these questions, we develop technologies that often have military or economic benefits (technology transfer). There's something about trying to solve problems humanity has not faced before that causes this. We talk a lot about solution spaces, but problem spaces are maybe more important! Second, there are intangible benefits to answering these questions, which accrue to those who answer them, but also to all of humanity. Prestige, soft power, research expertise, for the one who answers them. And for all of humanity, we gain perspective, awe, wonder, togetherness, curiosity, joy, a whole suite of feelings. If China discovers life on Mars first, which is absolutely a possibility, would we even bother with being second? I think it's too optimistic to assume it's inevitable that we will do a Mars sample return mission. And if we don't, we'd miss out on all the technology transfer benefits. Being in a race is very motivating.

Definitely haven't made a complete argument here, but those are my thoughts. I know there are more concrete, pressing issues out there. But we don't all have to save the world. We just have to do our part and be decent human beings.