In that regard, it was very ballsy, brave and risky - which makes it the very anti-thesis of POP.
If, as you contend, Pop was a total and utter commercial failure, then how can making an album which is the very antithesis of Pop be "very ballsy, brave and risky?"
Surely they had little to lose?
In POP, U2 took the easy way out. They tried to assimilate the "hot" mainstream music of that day to their music. You can hear the influences of The Chemical Brothers, Prodigy, and Beck in the songs in POP. U2 tried so hard to be commercial there and "ride the wave" of what was hot. The result was a failure because U2 tried to be someone they are not just to please the public and be current.
In ATYCLB, U2 stripped down and showcased their being a 4-piece band. They played music that can be brought to the road and played live. This was the exact opposite of the manufactured pop acts of that day which was the Britney Spears and boy band era. They went against the tide of what music was that day.
In some respects, ATYCLB was like Achtung Baby and The Joshua Tree. Achtung Baby went directly against the grunge movement of the Nineties. The Joshua Tree went against the power pop/rock ballads and new wave hits of the Eighties.
U2 make their best music when they go against the tide and not ride with it.
In POP, U2 weren't themselves. There is also some parallel with that and NLOTH where U2 were not themselves except for a few songs. Storytelling is not Bono's strongest writing suit and that should be left to other songwriters, or you will get junk like Cedars of Lebanon.
The Eighties had The Joshua Tree.
The Nineties had Achtung Baby.
The Zeroes had All That You Can Leave Behind.