Well, I think it is hard to generalize the way you have and be correct. I'm sure there are shops like the one you described - managers making much more than the devs, worrying more about their golf handicap than the project timeline. There are plenty of places though where the dev and manager payscales have quite a bit of overlap, where you'll find all of the senior devs making (much) more than the junior managers. I think this is right. At well-run companies there will also be quite a lot of pressure and stress put on the manager, simply because the manager is responsible for the success of every person on the team - so take all the things that can go wrong on the dev side (hit a snag and have to refactor, sick time, etc.) and multiply that by the size of the team. Good managers are also taking the heat for making the inevitable tradeoffs - "yes, we know big client X wants feature Y but we need to keep the release on track." Dealing with VPs several levels up trying to pull the project in different directions is also less than enjoyable.
Managers are also much more vulnerable to politics than individual contributors. You can be a great manager and still get canned if new upper management rolls in and doesn't like you or doesn't think you're the right person for their new policies - or if you get a tough project that doesn't go well and someone needs to be blamed. So, I think part of the compensation difference is because the job is simply riskier.