Personally, buying "one gun that can do it all" is a common mistake that a lot of new hunters make.

Unless you live in an area that has everything from prairie dogs to elephants, you don't really need one rifle to handle everything from prairie dogs to elephants.

Frankly, most hunters that don't live in areas that HAVE elk and caribou will never actually save up to go on a hunt for one, so it does them no good to own a rifle capable of taking elk or caribou. But there ARE guys (like myself) that live in areas with limited big game species, but save up to go on hunts in other states. For most people, this is a "once in a lifetime" opportunity, or at best, a couple trips in a lifetime.

If we're honest, a guided elk hunt costs about $3000-5000+, so if you NEED a different rifle at the time you get to go on your ONE elk trip, you can borrow or buy a different rifle for $500 and have the IDEAL rifle for elk, without owning and using the IDEAL ELK RIFLE on coyotes and whitetails.

"A master of all is a master of none" (meaning that a rifle that is "good for everything", likely isn't actually "ideal for anything"). Yes, a .30-06 can take anything in north america, but in reality, it's at the top end of the spectrum for deer rifles, and it is SEVERELY damaging on coyotes. If you're serious about coyote hunting, you really don't want a .30-06.

So, ultimately, if you live up north or out west where going on annual elk or caribou hunts along with your whitetail and coyote hunts will actually be common, then you need to plan for that. In that case, personally I would buy two rifles, say a .243win and a .300WSM or .338win. Just like I have a F-350 to haul stock trailers for the farm, but a VW Jetta to commute to town for work. It wouldn't make much sense to commute in the F-350, but that Jetta isn't going to pull a stock trailer either. If I had to pick one, obviously I'd have to keep the truck, but to make up some mileage, I could get an F-150 or 250, which wouldn't really be ideal for pulling a stock trailer full of 2000lb bulls, and wouldn't necessarily be good for commuting either, but "it CAN do both". Equally, I could get a .270, .30-06, or .308 that would be on the light end for big elk at long range (barely), and would be too heavy for coyotes. Personally, I prefer the two rifle plan.

On the other hand, if you live in say, the midwest, like myself, you really don't need a heavy rifle on a regular basis. Again, something in the .243-.270win range would be a great option for a coyote/deer rig. Then, on that year that you saved up enough to go on an elk hunt, you can buy a .300WSM, go knock down your elk, and either keep the rifle for prosperity, or sell it to regain some of your expense. If you're forking out $5000 to go on a guided hunt out of state, buying a $500 rifle that's ideal for the situation is a much better plan than 1) owning the ideal elk rifle and using it for 20yrs on nothing but whitetails, and 2) forcing your whitetail rifle to work on your once in a lifetime elk trip.

So again, ultimately, there are different cartridges available for a reason. Different cartridges are suited for certain applications better than others. Get a rifle that's ideal for the game you'll primarily be hunting, then evaluate how well it fits other applications.

Honestly, that's why everybody swears by the "5 gun list", that always reads something like "12ga, .22lr, .22-250, .30-06, .375H&H". With those 5, you really have a fairly "ideal" rifle for every application on the planet, even though the .30-06 or .375H&H would WORK for everything on the planet (obviously overkill for anything small).