The Russians are paying heavily to try to capture a small city they have mainly ruined already.
Wars are won when you inflict so much pain and agony on the civilian population that they turn on their own government. That is rule number 1 in waging war. Sad that people do not understand this principle. Cruel, yes but it is a fact.
You demonstrate a fundamental lack of understanding if you think that Bahkmut is just some small city in the Donbas region with no military value. Here is a map of the geography around Bahkmut for reference.
200,000 Ukrainians are dead and 400,000 dead and disabled.
Meanwhile, it is the Wagner group that has been exclusively doing the fighting on the ground.