Let's go ahead and take a look at Reach:
Source: http://forums.bungie.org/halo/archive36.pl?read=1068845 (Thanks, DEEP NNN)

"I use a simple copy and paste from Bungie's REACH project page around noon local time. Not all values were collected at exactly that time. Occasionally collection could be off by several hours. I only guarantee that I have made no willful misrepresentations by deliberately skewing collection in such a manner that poor conclusions or comparisons could be made or that any numbers presented are anything other than attempts to collect data from Bungie.

And now, Halo 4:
Source: http://halocharts.com/2012/chart/dailypeakpopulation/all (Thanks, firestream)

Full disclosure: I am not entirely sure how firestream gets these numbers, but I believe he relies on the Halo Waypoint webapp to get his information.

Assuming both of the numbers are accurate, how did this happen?

Halo Reach basically beats Halo 4's population by more than 10 times of Halo 4's "current" population.

Not only that, but Halo 4's Day 2 population could not even touch any of the numbers from DEEP NNN's Reach Population Chart.

It kind of makes me wonder, what were the possibilities for this?
Does everyone favor Call of Duty at this point?
Are there so many great games out there to make people not play Halo 4?
Do people just not have the time anymore to play Halo?
etc.?

What are your thoughts?