This seems to be a common issue. I suspected prior installation of the Xcode 15 RC may be related. None of the other fixes worked for me, but the following approach just did:
xcrun simctl runtime match list -v
Revealed the following:
iphoneos17.0: SDK Version: 17.0 SDK Build: 21A325 SDK Directory: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS17.0.sdk Platform: com.apple.platform.iphoneos Chosen Runtime: 21A325 User Override: (null) Preferred: 21A328 Default: 21A325
The 21A325 looked like an RC version. I then did the following:
xcrun simctl runtime match set iphoneos17.0 21A328
With this I was able to manually delete and reinstall the iOS 17.0 SDK the normal way within Xcode, and now, finally, all the iOS Simulators are shown.