My pet hypothesis is that Putin and Prigozhin were engaging in a bit of play acting to stage Wagner troops for an action against Ukraine (Prigozhin benefits) and illustrate the legal and financial measures that Putin will take against powerful dissenters (Putin benefits).

With 25k troops, there's simply no way Wagner could have succeeded in a coup. The regular army is better equipped and could have severed their supply lines with minimal effort, starving the coup with minimal bloodshed. They could have done this in their own interests, and not necessarily in defense of Putin.

Considering how swiftly Wagner's offices were raided and their assets seized, this affair makes more sense as a morality tale to caution antsy oligarchs than as a military action.