The Boring Company isn’t asking Chicago for any money to build it (which is great! Chicago is broke due to pension obligations and historical graft/patronage), and will support itself off of use fees. It will be 100% privately financed. This is no different than how the Illinois Tollway is operated (and while the tollway is plagued with oversight, governace, and corruption issues because Illinois, Musk can have the benefit of the doubt).
Sidenote: If the CTA is chronically underfunded, and the city is broke, perhaps the $2.25 fare the author mentions is structurally unsustainable.
I’m not going to judge so fast and say that he’s not humanity’s savior, because I don’t see a lot of folks with his resources pushing in the right direction like he is (despite him appearing to be on the spectrum and occasionally a shit person). To be determined.