Russia is 100% concerned about them as they were both good friends with Putler. Iran won't be helping Russia out much anymore with the state of their country just like Syria has moved on from Russian influence. Who knows maybe killing and oppressing your own people isn't a thing anymore.
Russia does not give two-shits on who is ruling Venezuela as long as their influence in the country continues. ...and it will. Maduro will be replaced by another corrupt Venezuelan leader. Just like in Ukraine with Zelensky.
The Iranian government supports Russia, not the Iranian people. Also, corrupt leaders in Iran.
Russia still has significant influence in Syria. They too have a corrupt leader.
Corrupt countries are easily influenced by Russia and China. Corrupt leaders care only about money and getting rich, not the people they are supposedly ruling over.
Were you born when the U.S. captured Noriega in Panama in 1989?
How about Somalia in 1993 when U.S. forces captured about two dozen Somali militia members during a raid to seize leaders of warlord Mohamed Farah Aidid?
Do you think Trump should send U.S. forces to Moscow to capture Putin? Maybe U.S. forces to Ukraine to capture Zelensky.
Trump will soon be taking military action in Iran. Again. Military strikes or maybe even the U.S. Marines

.
Were you born yet in 1980 when the U.S. sent forces to Iran to rescue 52 American hostages? Operation Eagle Claw. It turned into a complete disaster. A big "Black Eye" for U.S. Special Operations.