I completely agree with your concern. The money we’d spend getting to Mars can be spent further developing our understanding of Earth and making our life here stable before we seek to venture to new worlds. I don’t think we should wait forever to become a multi-planet species but we should at least make sure Earth’s climate is stable, our animal species aren’t going extinct, and we can feed our people without draining all our resources. Because at the end of the day, no matter if we can use this lake on Mars or not, we’ve been designed to live on this planet and not any other. Mars will never accommodate us the way Earth does.