I think it might be easier to count those that don't own more than one rifle.
You've got hunting rifles: standard hunting rifle, long range carry rifle, long range ain't going to carry it very far rifle.
Then you got your varmint rifles: short range varmint rifle, long range varmint rifle, and you better have a walking varminter to even out the pack.
But what if one rifle is out of commission for some reason? That's where the back up rifles come in, and the back ups for the back ups.
And what if you want to take a girfriend/niece/nephew/neighbor/etc., or all of the above out to learn to shoot and/or pop some squirrels? Half a dozen rimfires and you should be good to go...don't forget the back ups though.
Then there are the project rifles. Problems can and do arrise during projects though, thankfully you've got the back up projects too.
I'm sure I missed a few, someone else will probably jump in and point them out.