They didn’t slaughter their way to unity because: 1). Change in leadership, 2). No money, 3). Shake up of natural/governmental order

Why would they use nuclear weapons, pissing off the wider world, while habit very little to no effective military capacity?

Those satellite states were offered referendums to leave. Should Russia have changed government, went back on their word and start taking over the land? Again, pissing off everyone?

Nothing you’ve said proves anything, it’s just silly talk points that have no basis in reality. The USSR collapsed. Russia didn’t have the capabilities to pursue any world doctrine.