My time is in Barons and Aztecs. The 421 is many times more expensive than a King Air depending on avionics and cabin interior. It’s a very fast unforgiving airplane. I worked at several airports on the general aviation side for about 30 years. I owned my own plane for 25 years.
I flew for 40 years, all of it in singles and light twins.
It is amazing how many people I knew personally, some were good friends, were killed over the 40 years.
Many in single engines as well as twins.
Circle approach at night below minimums, Instrument flight to summer home after fight with wife, jet fuel by inexperienced lineman (an Aerostar). two who died on bets they could roll inverted at field boundary and climb out, another roll on takeoff at an air show, another hammer head stalls in borrowed aircraft overloaded and out of CG....
I once counted them all up but that was so long ago I don’t remember how many....but every one of them single or twin were causes by pilot error or maintenance or fuel error. And yes, I even knew one who was so good he regularly flew a Lockheed Electra off a 1800 ft. grass field on a small ridge. But it did not end well the day he forgot to take the lock off the controls. That was the old Electra similar to the one Amelia Earhart flew.
And my point is every one of them would have been killed had he been in either a single or twin.
Another Aerostar owner, a business associate died in, could be blamed due to its characteristics on final but I had the unhappy experience of riding in the back seat once with him and swore never again, so even in that crash I declare pilot error.