I'll make a rental-based comparison.
Brand new Cirrus SR22TN, FIKI, all the bells an whistles - around 360 wet. 195kt cruise at FL180.
30 year old twin, turbo, FIKI, all the bells and whistles, but ancient bells and well-worn whistles. Very well maintained, though, everything works. 170kt cruise at FL180, over GBP 500 wet. Airways charges on top.
In both cases I am certain the owners do not make much of a return from renting it out. In the last 10 hours of flying the twin, there were a few thousands worth of troubleshooting and repair (starter motor, RMI, one CDI - and as it is well maintained everything gets fixed).
The yearly maintenance bill is easily 5 times as high than the comparable figure for the single.
Yes, that particular twin can be bought for less than a third of the price of a good used Cirrus, but if you look at a ten year period the new-ish single will be MUCH cheaper.