On a purely Machiavellistic level, coups with an inside element helping along (and that is what Venezuela was: Delcy Rodriguez going full Judas on Maduro) are a distinct phenomenon with a different profile of risks and rewards. As you say, even today, they may pay very well - but precisely because they don't lead to a large-scale war with all the destruction it entails.

Iran is a true war, where the local elite didn't even partly defect, and it is already becoming an expensive quagmire with nothing of value gained.

Of course some politicians do mistake one for another. Putin in 2022 probably expected a swift coup by his crony Medvedchuk, who instead turned tail and ran. Instead he got a brutal war of attrition.