So its 7am, east coast time. Wait time is at least 7-10 minutes before i find a game, whether is BTB or slayer, wait time is very long. Even afternoon, is the population really that low?
It depends on your location player amount pretty much, because if your game cant find any players at all it will usually say "Cannot find find enough players to support game mode" something like that I guess. Dont get me wrong Halo 5 does have a big player base at the moment like me in Australia I usually more likely to find a Warzone game then Arena.
All the kids are in school at this time. 
I thought you were going to sell the game? Just do it already
Just sell the game so you can leave these forums!
I’ve never waited a moment, even in the mornings, to find a group. The community may have taken a hit but it certainly wasn’t that extensive! And I imagine it will only improve from here.