Who told them it was being stolen? - Liars, known liars. Not a shred of evidence to back it up. They wanted to believe, without facts to back it up. They wanted to overthrow the government. Truth be dammed.
Yep. That’s why this whole “Oh, it’s not a coup because the rubes actually believed the lies about a stolen election” is such complete and utter bullshit.
When is an attempted coup not an attempted coup? When it is successful, of course, the very moment it becomes a glorious heroic patriotic revolution.
That is the moment whataboutism reverses the polarity and the other side has to justify itself (or is simply thrown into jail, what do you think those jails are for?) while the rioters - now patrioters - bask in the adulation of the masses during a never ending victory lap. Confetti! Champagne! Fireworks! Blow jobs!
I would guess that close to 100% of them would say that “install Donald Trump as President for another 4 years” was a primary motivation.
And they really believed that this was possible, thanks to the concerted efforts of Trump and his co-conspirators. They believed the lies, even though the election wasn’t even particularly close, it was the widest margin in a U.S. Presidential election since Barack Obama’s 2008 victory.
And that constitutes an attempted overthrow of the duly elected executive branch of the government.