The US & Nato's industrial production is inadequate to the task of supplying adequate munitions.
The Russian population is 3.75 times Ukraine's. Yes Russia is losing more men than Ukraine. But Ukraine's manpower is finite.

I'd frame it more as the US and NATO are unwilling to supply adequate munitions. I'd also say Russia's industrial production isn't up the task either. Russia is just about out of armored vehicles and troops now enter battle on ATVs and electric scooters. Yes, electric scooters. This results in very high casualties, but the Russians are able to "flood the zone" using superior numbers.

Today's ISW report had a good summary of Russia's negotiating position.

The sources reported that Putin continues to demand that NATO fundamentally alter one of its core tenets and commit to a legally binding pledge not to expand eastward, a demand that would require the renegotiation and re-ratification of the NATO treaty by all NATO member states. Lavrov recently stated that the Kremlin's objective is to politically control all of Ukraine rather than to seize select Ukrainian territories such as Donetsk Oblast, further demonstrating that Russia remains unwilling to accept any agreement that falls short of Ukraine's full capitulation.

understandingwar.org - Russian offensive campaign assessment august

Russia isn't offering anything that would be remotely acceptable to the west or to Ukraine. And Russia has been very consistent on this policy since the war began. Since Russia will not negotiate, IMO the only rational option the west has is vastly increase the amount the aid to Ukraine. The cost relative to the size of the defense budget isn't very much, we'd be neutering one of our biggest geopolitical foes which is the purpose of the defense budget in the first place, and most of the money is spent inside the beltway anyway.