Shall we play a game? It's called global economic/military strategy, with a huge helping of psychological manipulation thrown in.
He knows that Europe is working on efficiencies, process changes and new suppliers for his natural gas. His time is short to use this for leverage, which may explain him pushing this issue right now to get what he wants, which is a big chunk of the Ukraine and assurances that the rest of Ukraine will not join NATO. Vlad also desperately needs a psychological lift to his presidency (or whatever the hell he is) and the overall Russian psyche; getting these concessions would give him that, for now at least.
Europe is also leaving a winter, not entering one, which does not play in Vlad's hands at the present.
Europe can address the natural gas/oil issue a lot quicker than Putin can change Russia's one trick pony economy into a multi-faceted and diverse economy where the price of one commodity, one, cannot send your entire country into the doldrums. Another reason Putin thinks he needs to act now.
If the West grants Putin his two primary objectives, will this historically turn out to be a good thing or a bad thing? The West has most of the cards right now; they do not have to give Vlad anything. But is that the wiser move? Germany likely thinks concessions should be made, but without some assurances from Russia that they will leave the rest of the Ukraine alone, the Baltics and every other target Vlad may have alone, this strategy is at best a paper strategy relying solely on the individual players.
Vlad is taking a risk right now that, from a war games strategic posture, couldn't be made at a worse time. Go big or go home I suppose. He is banking on the West not forcing a long, protracted, expensive and ugly war in the Ukraine. The West can better afford the costs, which would primarily be enough military support to force a stalemate and enough economic pressure to make Russian continue to feel it. Amping up the military option results in lost lives and the potential for unintended consequences however.
It's why these guys make the big bucks.