Can PPL, CPL, and ATPL be completed within a year?
Given the hours required for the ATP, the chance of doing that rating alone in under a year seems pretty remote.

Getting the private and commercial certificates done inside of a year is entirely possible, although not cheap. The writtens for the ATP are no big deal, but the hours simply will take a lot of time, as well as the right employment opportunity, to get.

The number of FO's at smaller (regional) airlines who have been flying for several years but who don't yet have their ATP attests to the time required. You can (and generally have to) pay for the flight time to get your Commercial, but paying for all the flight time required for an ATP is simply beyond those of whose last name isn't Gates, Bezos, Trump, or etc.