You are conflating things here. Yes it seems like the one thing you mention, but is really from the Russian perspective something else - acquisition of hard currency is one major Russian objective - profits are nearly unknown in Russia - accumulation of money by some oligarch is not the same thing as the Western idea of profits.
Russia is only “undermining US power,” if you imagine that is Russia’s long term objective - but it is not historically - rather it is securing the boundaries of its nation, and the surrounding territory to make invasion difficult, as well as the historic quest for warm water access - hence the retaking of the Crimea.
If Iran did something terrible to Russia, Russia would have no qualms about using nuclear weapons on them. In fact that is their military policy. Russia has a totally different perspective on use of nuclear weapons than the West - this from a nation which developed its nuclear program by handling plutonium with bare hands ...
Remember Iran is the Mexico of Russia and all that flows from that sort of relationship - much as ours does with our southern neighbor.
Trust me. They collaborate on things, like Intel and other operations.
Russia didn't push the USA out of Kyrgyzstan because it's on the Russian border. Russia, under Putin, aspires to much more than taking care of its borders. It doesn't need to send its bombers in to the airspace of neutral nations to protect its borders. It doesn't need to send its submarines into the territorial waters of neutral nations to protect its borders.