Millions? I don't think so. There is no investment that would turn $30K or whatever into millions that was safe enough to work for the majority of people. But it would be a significant help.
That being said, for most people, the amount you'd spend to live in a place where a car isn't needed or constantly paying for ride share or taxis greatly exceeds the amount you'd save by not having a car for the vast majority of people, and that's not even getting into the ableism issue.
And sure we could get into buying a cheaper, used car or whatever, but in the long term the maintenance costs, having to buy another car sooner, and other financial risks to cars outside of warrantee over a lifetime will add up similarly unless you're really lucky or can repair your own cars.