WHY WOULD ELON MUSK PIVOT FROM MARS TO THE MOON ALL OF A SUDDEN?

Summary from the TLDR newsletter

SpaceX is pivoting its focus from building a settlement on Mars to building a 'self-growing' city on the Moon. Elon Musk says that a Moon settlement could be achieved in less than 10 years, whereas Mars would take more than 20 years. SpaceX was founded with the original goal of settling Mars. However, focusing on the Moon, SpaceX is making a decision that benefits NASA and the US.