I think we actually can change everything. But there are a thousand variables to consider. Like how much time and energy it would take us, which then has to be balanced against our priorities. We could become president and so on. It's just not worth it.
There are so many things that we can change and have a better coefficient of energy put in and change initiated. Our children, for starters. HUGE change that we can invoke through raising them right, according to our values. Multipliers of change in a way. And for most of us, the energy capacity and time on earth limits us to either becoming president or raising children right.