I'm pretty sure it's because he lives there. Not only does it make it easy for him to be involved, but it sounds like he really hates LA traffic and really want

I'm pretty sure it's because he lives there. Not only does it make it easy for him to be involved, but it sounds like he really hates LA traffic and really wants to bypass it for his own personal benefit. He announced the company saying "Traffic is driving me nuts. Am going to build a tunnel boring machine and just start digging..." and the proposed route happens to be convenient for him: https://www.fastcompany.com/40500593/elon-musks-tunnel-through-l-a-just-happens-to-go-from-his-house-to-his-office https://www.fastcompany.com/40500593/elon-musks-tunnel-throu...