I don't have any theories...perhaps something about the futility of trying and caring. Thom Yorke can be pretty...ehhhh, cynical about life. I don't think it necessarily reflects the words of the song, though. The song, to me, has always had a sort of
Instant Karma kind of message to it. I used to sing it to my kids when something backfired on them that they shouldn't have been doing in the first place.
You do it to yourself, you do, and that's what really hurts, you do it to yourself, just you, you and know one else, you do it to yourseeeeelf, you do it to yourseeeeelf
Hah! They loved that, lol. But it would make them smile a little.
At any rate, me LOVES Radiohead. In fact we are a Radiohead-loving family.