There have been multiple threads on this topic recently, and I suspect there will be more.

I think the reason for this is rollover. Many folks who would make FO year after year rolled over enough MQMs from last year to get them close to GM or make them GM.

The general thought is that the value added of GM is significant. However, if you barely make GM, you will not roll over many miles. If this means that you will potentially not earn 25k MQMs next year, then you could go from FO to GM to general member.

Thus the consensus seems to be that go ahead and make GM if you are sure you can at least make FO next year. If not, stay at FO, roll over lots of miles, and make FO easily next year.