Let’s say some extremist, highly organized group manages to successfully assassinate the 10,000 richest people in the world, and then disappears without a trace.

The problem is that these billionaires profit the most from a system of resource exploitation, but they do not benefit exclusively. We'd still have hundreds of billions of dollars in fossil fuel centric infrastructure that we'd need to replace and reconfigure. And that reconfiguration would require a national organized effort.

Ultimate, you can't just wave a wand and make Rich People Go Away. You need a national project that is both popular and efficient. One that reduces emissions while improving quality of life. You need a Green New Deal.

That's not something you can affect purely from subtraction.