Since I have a .223 Rem and a .270 Win, That combination will cover most shooting and hunting that I do, especially with handloads. So why, you ask, do I own 3, .243 Win rifles? Because they fill a need for a wind-bucking, low recoiling large varmint/range rifle. It bucks wind and hits hard. One can also see dirt fly on near misses, not like the .22-250 and .223 rounds.
When shooting my first .243, I was very impressed with the power of the cartridge, compared with the .22 centerfires. Using 80 grain Hornady GMX bullets, it's a formidable deer round to about 250 yards and is used by the grand-kids with good results.
No, a person just can't own one rifle in a caliber that great.
People are like rifles. Some are tried and true, having great eyes, personality, and fun to be with. Others never seem to hit the mark with you. Still others go off half-cocked. Still, it's nice to know most of them.