I agree with you partly on your first point. Putin has other ways of making his fortune. BUT that doesn’t mean that he couldn’t also do this. Maybe it’s not the primary reason, but if Putin doesn’t care about Russia or the Russian people, then money could be a motivator.
On your second point IDK though. Russia still has a pretty large black sea port in Novorossiysk to the south east of Crimea. That port is on the mainland, has a rail connection, and doesn’t rely on an explosion prone bridge. Sevastopol may be an important port, but important enough to go to war over? Besides, the black sea ports aren’t the only warm water ports west of the Urals. Not counting the unconnected port in Murmansk, on the Baltic sea there’s Kaliningrad and the three large ports near Saint Petersburg. On wikipedia’s list of largest ports in the Baltic sea, the three at Saint Petersburg are in the top four.
So why go to war for a fifth port? Was Novorossiysk operating at capacity? I dont buy it. The war wasn’t for a path to Sevastopol alone.