Best alternative to colonizing Mars! We shouldn't put all our eggs in one planet, but where should we go?

If we have people living permanently off Earth, it will be much easier to detect objects that could potentially threaten Earth because we will be able to observe the area surrounding Earth without the interference of an atmosphere. If we detect an incoming object that could potentially cause harm, it would not cause panic because we will be more experienced and prepared to handle such threats. For example, if a micrometeorite were to puncture a wall or window on the Moon, a seasoned space inhabitant would know how to quickly and efficiently fix the issue, rather than panicking. In general, being prepared for potential threats and having experience living in space will allow us to handle such situations with efficiency and calmness.