Everything is a certainty given enough time.
In addition, Mr. Buffet may be a great investor, but what exactly how much would he know about terrorists or nuclear weapons? Probably as much as you and I.
Because the facts of each iteration can completely alter the whole chain.
This is the argument that if you flip a coin enough times, heads MUST come up. But that is in fact not true. Each flip is completely independent of the last flip. Given enough time, there is in fact no law that says heads must occur.
Real life events work much the same way. Any given event can be interrupted. The 'everything is certain' premise doesn't work if a human exists and can stop or alter the process with free will (in any number of a zillion variable ways). For example, Buffett's calculation says that after, say, 100 years a nuclear bomb essentially must have gone off, but that's not true at all, because people can always stop it from happening and interrupt the theoretical math calculation (which only actually exists in a 'vacuum'). In any given year, the odds are N, but that does not in fact compound into following years inherently.
No, it's the argument that given enough time, it is certain that something as unlikely as a direct meteorite strike on Earth will happen. Low probability x infinite timeframe = %100 occurrence