A very significant part of Russia is permafrost. As climate gets warm, more of permafrost land is melting. It's not really clear the consequences of this process. It releases trapped CO2, it changes ecosystems, it transforms solid land into a swamp.
I'm not claiming that you're not correct. Cold climate requires spending truly enormous energy and resources to heat people, to build warm houses, to craft warm clothes. Cold climate harvests very lesser amounts of wheat and other plants and animals. This is extremely big part of equation.
There's a fun youtuber called vagabond, who train hops around Russia and Europe.
He had a video showing buildings build on permafrost. They lift the buildings up off the ground so none of the heating heat touches the ground and weakens the foundations.
I fully expect if the permafrost goes soggy, most of the settled north will just sink into the bog.
I'm not claiming that you're not correct. Cold climate requires spending truly enormous energy and resources to heat people, to build warm houses, to craft warm clothes. Cold climate harvests very lesser amounts of wheat and other plants and animals. This is extremely big part of equation.