I will go with the past few months; the recent public political statements aimed at the US policies and the release strategy for SOE, followed up by promoting 2 clunkers off of the album (american soul, get out), the performances of said clunkers, and the icing on the cake would be the awful GOOYOW video.
Nothing the band has done up until this point has really bothered me, all of those supposed "low points" of the past; Rattle & Hum, PoP, the cringeworthy politician photo-ops, the 09 Grammys, the SOI iphone release, none of those really bothered me as much as what has taken place over the past few months.
As u2 ages so does a lot of their die hard fan base. Also, at least here in America, a lot of people who were very liberal in their youth tend to grow a bit more moderate to conservative in their middle age. The fact that u2 seem determined to use their stage to sound off on current american politics at this particular time is a huge turn off for a lot of people who once loved them and would have followed them to the ends of the earth.
That said, i don't really care what they think deep down in their hearts, i just don't need to know it or hear it every time Bono opens up his big mouth or with every new song. Just because someone is rich and famous doesn't make their opinion more valuable than anyone else's.