They are obviously still making lots of money by circumventing the sanctions. I suppose another option would be to flood the world with cheap oil - making Russian oil less valuable. But that would mean upsetting oil companies, and there isn't a politician alive (for long) who does that successfully.
...I'm having trouble squaring this conclusion with the fact that generally, it's the Democrats who want to choke off oil production, and Republicans who are on the "drill baby, drill" train.
In terms of running out of bodies and resources, Ukraine will run out long before Russia.
Russia has a much bigger population, higher GDP per capita, far more financial reserves, and their industrial base and infrastructure are relatively untouched, notwithstanding isolated drone strikes on refineries. As if this war wasn't lopsided enough, Russia also has the manufacturing capacity of Iran, North Korea, and China at their disposal. Economic superpowers India and China are buying their hydrocarbons, so sanctions are simply Western hand-washing. Russia is recruiting mercenaries from China, Nepal, India, Syria, Cuba, Venezuela, and its colonized parts of Africa.
Ukraine is the underdog here, and will eventually run out of soldiers and infrastructure. The Western plan to trickle intermittent, old supplies to Ukraine in order to weaken Russia is about to reach an inflection point, where a decision will have to be made to actively save Ukraine or not. It is doubtful the U.S. will do much more, with most of the Republican party on Russia's side. The Poles, Germans, and the Czechs may take a more active role in the absence of U.S. leadership.
So far the Ukrainians have been smart to mostly play defense, inflicting asymmetrical casualties on the Russians amid meat assaults on the open Eastern minefields. This is buying time, preventing greater losses, and bringing the two armies slightly closer to parity in terms of vehicles and soldiers, but it is also consuming scarce ammo and soldiers at a probably faster pace than Ukraine can replenish them. Russia's massive advantage in artillery shell production threatens to turn the tables on Ukraine's defensive strategy.
I'm a bit more optimistic. Russia may have a huge manpower and artillery
production advantage, but that's about it. They can't produce aircraft at any appreciable rate, they're losing armor far faster than they can manufacture it, and they've been stripping all of their storage yards of armored vehicles for two years. At their current loss rates, analysts are estimating Russia will run out of armor in 18-24 months. As for foreign recruits, I've seen the anecdotes, but haven't seen any statistics about how many they number. Meanwhile, the West is sitting on
thousands and thousands of old Bradleys, hundreds of F-16s, thousands of Abrams, etc. You're absolutely right that artillery shell production needs to be ramped up in the West more than it is. Rheinmetall is going to build multiple plants in Ukraine in the near future.
There's also the internal economics and politics of Russia. Sure, Putin has a stranglehold on power, but he's trashing the country's economy in the meantime. Last I heard, inflation is at 16%, and sending three quarters of a million working-age men to invade Ukraine doesn't come without a cost. That gets even worse when you have to pull another who-knows-how-many out of civilian industries to support the war, and
even worse when your population pyramid looks like Russia's, and compounds further when you consider the enormous brain drain that happened when this misguided escapade started and everyone fled who has the money and/or brains to do so. Ukraine is facing the same issue for sure, but there's a lot of western money flowing in to help support their economy.