Putin has been in power for 25 years. He arguably has more enemies than anyone else on the planet. I’d say the deterrent factor is pretty strong with this one.

It’s not perfect though. When you’re destroying your own country with the most disastrous war in living memory then you need stronger deterrents.

In some cases, the people in power change their minds and suddenly an oligarch who was compliant becomes a target.

As chonglibloodsport said, it's a numbers game.

When you have enough enemies, and keep making more, you're going to keep getting people who have had enough and don't care about the risk.

If it weren't for the "Russian suicide", putin would have been black bagged long ago by someone who WOULD.