I’ll tell you how conspiracy theories start. Just like the game of Telephone, or this thread, as a matter of fact. Someone hears something, changes it a bit, and passes it along to another someone who makes things up.
And so, there was no Polish Prime Minister murdered, and, a minor detail, there were 96 on the board of the plane.
That the Russians caused the accident is doubtful.
I agree with you about it being a conspiracy theory, but going by the history of Poland where the Russians have been playing intrigues since the 18th century, it's a bit easier to understand why it's to be believed
Also note that the Russians were pretty slow to get to explanations, the investigation was haphazard etc -- breeding grounds for a conspiracy
That the Russians caused the accident is doubtful. -- improbable, yes, but going by Russian intrigues, not impossible. And that's the catch -- in Poland it's easy for Poles to believe the worst about the Russian government