One rifle when chosen wisely can do it all if it were the only option financially, imo. I think that not all but most of the time when someone has and uses different guns, they just like guns and the shooting sports.
I'd pretty much agree with that.
I don't "need" ... well, let me go double check the count ... eight. I don't "need" eight 'elk rifles', but I sure do like to have them available.
There's the drop-dead-reliable iron-sighted bolt action carbine shooting a cartridge that predates .30 U.S.: the M38 Mosin-Nagant.
There's the single-shot .444 Marlin that's tough as nails, but dirt cheap and dirt simple. Short, light, and handy.
Both of the above excel at helping me not give a crap about them. Good chance I might take a tumble on the rocks that have some fresh snow and smack the rifle today? Grab the Mosin or Handi-rifle.
And there's the bolt action .30-06 that is oh so much nicer to carry in the mountains than my .270.
That .270, itself works very well, but it's a beast to lug around on long hikes. It's an 'elk rifle' but one I often reserve for time spent sitting and watching.
And then there are the short-range / snap-shot options, and the .35 Whelen, and more...
And, hopefully by the end of the year, I'll have yet another one in the lineup: another .270 Win built on a commercial Mauser action (but with a shorter barrel, and a bit less weight than the current .270).
I don't "need" them, but I thoroughly enjoy each and every one of them for the different ways in which they excel and the ways in which they allow me to modify my hunt.