Building more road capacity to fix congestion never works. Ever. This is highway planning 101: more roads/lanes creates induced demand until travel times are exactly what they were before construction, and so you just spent a billion dollars to go nowhere.

For an illustrative example, look at what Houston did to the I-10: they thought like you did and decided to just build and build until the traffic went away. There’s a stretch of I-10 outside Houston that is now twenty-six lanes wide, and it didn’t work: within a few years of completion, travel times returned to what they were before the buildout. Exactly how many lanes do you think will fix the problem if 26 won’t?

(And even if it did, there’s no more room in Manhattan for more roads. There is no way to increase supply even if we wanted to.)

Which, if you think about it, makes perfect sense. Everybody has some unconscious limit of how long they are willing for their commute to be. Am I willing to commute for 30 minutes? Probably. What if it was two hours? No way. I'd either find a closer job or move closer to work.

Average that over the whole population, each with their own individual unconscious time limit. The result is: if commuting is faster, people are willing to live farther from their jobs. If commuting is slower, people live closer to their jobs. Adding more capacity doesn't change this.