Its well spent money for Germany..especially if the Allies intervene in the Winter War, AND, Finland wins the Winter War, thus preserving its 1939 boundaries. The USSR is double fubared. 1st, Soviet mobilization goes down the toilet, and 2nd) The Finno-Soviet 1939 boundary abuts Leningrad, Belomorsk, and Kandalaska.
If the Allies intervene..Finland goes 15% pro-Allied. Time for Axis diplomacy if you wish. Why? Because upon Germanys declaration of war on the USSR..Finland will join as long as its pro-axis, as explained in the rules. Not 15%, not 50% nor 100%. No..all that is required is 1% pro-Axis for Finland to join. With Finland in, then Germany can decide in the future if she wants to use Soumi as a launchpad for invasion or not.
Cutting the RR line at Belmorsk is a bonus, because Murmansk is the only ice free port the USSR has in the European Theater. If the line is cut..the UK-USSR convoy goes to Archanglsk, which is bound by ice in the winter, thus again closing the convoy like clockwork, every winter. :)
Epekepe witnessed me doing this in an MP match on YT. I spent a total of about 400 MMP to do this thing, and got not only the deployed units including a valuable fighter, but in addition, bought everything else Finland could build. It was well worth the investment that gave my Axis another option.
But again, the operative question is not whether it is money well-spent. Rather, is it "better spent than investing in Turkey, Spain, or Italy, etc.?"