Because he thinks his genes are so fantastic that it’s his offspring that should rule?
BTW, this isn’t an uncommon thought amongst the ultra wealthy. Why do you think none of the oil barons, who know damn well global warming could make the earth largely uninhabitable in the future, don’t seem to care about their children’s legacy, or that of their grand children?
It’s because they know that if their descendants inherit enough wealth, no matter how bad things get, things will probably be ok for them. Because they will be able to afford whatever the upper echelon of society has to protect against the conditions. And they secretly hope the demographics that comprise the under class will die off due to the changes in climate. They feel anyone who is poor has bad genetics, and that they are wealthy because they are somehow genetically superior.
I’m sure Musk is the same way.