This is a very valid question and we should all be asking this. Mars has approximately 200 estimated asteroid impacts per year (https://www.space.com/21198-mars-asteroid-strikes-common.htm... - a bit dated) while earth has about 10-12, most hitting water. The vast majority disintegrate in our atmosphere (https://www.hq.nasa.gov/office/pao/History/impact.html).

While I understand the need for us to look to the stars and dream big, if catastrophic destruction is the primary driver for looking for settling on Mars, we should ask if Antarctica might be a better first choice.

average person on Mars would be much better prepared to the impact.

While the environmental impact would be minimal (primarily because there's not much environment to speak of to begin with), no one can possibly prepare for a direct hit on the head.

Access to rocket would be greater on Mars so you can temporary evacuate. Access to tools to say underground etc.

All of this can be built on Earth, much more easily