Lots of people have a dozen or two dozen long guns for some reason I can't understand. I can understand having several ..... but once you have those I don't see what more you would want as you'd have all the bases covered.
Some of us get guns "after we have our bases covered" simply because we want to check them out. See if they do what we want, better than, worse than, or the same as what we already have. Sometimes the "extras" are something specific about the gun, not the caliber. (for example, I've got a couple 9mms, why would I want a Luger?? Ans: Because I WANT a Luger!, etc.)
Why does a golfer have a bag full of clubs, when one, or two will cover all the bases??
Why does a fisherman have a tackle box full of different lures? aren't worms enough???
What additional options will a revolver provide that I don't already have?
Let's see, what options does a revolver provide over 9mm & .22LR semi auto pistols??
The option of dropping your fired brass into your waiting hand, is one. (not having it find it and pick it up)
The option of feeding any and every style of bullet without any real concerns or reliability issues...
The option of the mechanism cycling exactly the same (other than felt recoil) with everything from cat sneeze to roaring monster magnum level loads.
The option of different calibers...
The option of not having all the vulnerabilities of a detachable magazine. (dropped, LOST, damaged feed lips, etc.)
The option of having vastly different classes of gun in the same caliber, to a greater extent than is common with semi autos.
And the option of a different feel, a different kind of grip shape, the option to more easily customize the grip size and shape...
and others, depending on the specific guns you are talking about...
Revolvers offer a very wide range of versatility that semi autos generally don't. There are some jobs that semis do better than revolvers, absolutely. And, the reverse is generally true, as well.
There's other points I didn't mention, as they don't apply to your situation (yet
)