> How can anybody believe such nonsense?

Because the intelligentsia aligned with the “retain power for Trump at all costs” faction represetned in the insurrection announced various mechanisms by which that ccould be done (which may be Constitutionally dubious, but that’s irrelevant here), because the President openly endorsed those theories, and because the actions the members of the mob openly stated they wanted to take were consistent with enabling those routes to be taken by removing actors who were impeding them, notably the VP.

To believe it was an attempt doesn't mean that you must believe it was likely to succeed, only that there is sufficient reason to believe that that's what the actors involved wanted to have happen. And there's plenty of reason to believe that they did want to impose a different leadership than the actual election winner, and that they had specific reason to believe that attacking the capitol when they did would present a means to achieve that objective.

> Sorry, but simply taking over the capitol doesn’t automatically make you the ruler of a new regime.

Nor was that the plan, but the escape of the VP and members caused the plan to fail.

It's not the protesters that made it a coup, it's the fact the security forces of the country allowed it to happen.

Angry protesters are a dime a dozen, it's the letting them into the main government building that makes it a coup.