Europe started using Russian gas in the 80's and has plenty of domestic coal reserves. As to infrastructure costs - it's something they would have had to eventually do in order to take advantage of far lower gas prices in the Americas, as well as reduce their exposure to disruptions due to Russian expansionism.
The Germans now seem willing to accept Russian expansion into eastern europe in exchange for Russian gas. I am stunned by the timidity of the Germans. They are not stupid and have to know Putin won’t stop with Ukraine. They don’t seem to care.