Germany has definitely been spending money in becoming independent from Russia on the energy front, though indeed whether they've right now passed the peak in terms of cost for their Economy and on the other side of that specific hill or not, is something that only Historians will be able to tell in some years' time, and neither you nor I can prove it either way.

However Germany is not the whole of Europe.

In fact for all its size as a nation Germany is only about 5% of Europe (8% of the EU) both in number of people and economically. Further, it was one of the most deeply tangled with Russia and is one of the most behind in becoming independent of Russian hydrocarbons (all of which probably explains why Germany was so hesitant to start supporting Ukraine at the beginning of the Invasion and in entering every new stage of military support - like sending tanks and sending fighter jets - since, and why in proportion to their GDP their support to Ukraine is at best mild: the really winners how much of their GDP did they spend in supporting Ukraine are all Eastern European nations).

You might have had a good point in your original statement if you wrote "German leaders" but you didn't, you wrote "European leaders" and no matter how good the case you make for Germany alone, that's not the same as all of Europe, and Germany being in the worst possible starting position of all of Europe (except perhaps Hungary) when it comes to dependency on Russian fossil fuels means that even if you had actually proven a willingness in the German political class to "just let Russia have it" when it comes to the Russian invasion of Ukraine because of Economic reasons (which you didn't, although you did make a good case for it to be so), that has no relevance for the other 95% of Europe, of which already the leaders of two large countries - France and the UK - who together easily add up up to more than Germany have very loudly voiced their wish of continuing to support Ukraine and started testing the waters with Public Opinion on sending their own troops there, with most of the Eastern European nations and even the Scandinavian nations having also loudly confirmed their continued support.

Back during the Leave referendum campaign, the Brexiters repeatedly claimed that the UK after leaving was going to still get full access to the single market in almost as good conditions as an EU member, but without obligations such as Free Movement "because German car makers will make the EU do it as the UK is such a large percentage of their Revenue". Ultimately what was proven was that by itself the Economic interest of Germany and its large companies won't move the whole of the EU to do something that's against the interests of most of its nations unless there is a large block of countries predisposed to it, and in this not only is "the threat of Russian Imperialism" an existentialist matter for most of Eastern European nations, but the leaders of most EU nations have come out strongly in favor of continued support of Ukraine, and even the newly elected German Chancellor has made statements to that end (though certainly not as strong as the likes of Macron). Given the proportion of Europe who are EU members, even if all the non-EU European nations sided with Russia (as the likes of Servia have done) it would still be a small fraction of the total and far from enough to justify your broad statement about what "European leader" might be feeling so you would have to show that most of the EU had such a predisposition and as recent History has showing Germany and their interest alone are far from enough for that.

What has happened in the beginning of the Invasion and in every new step of expanding the types of military support for Ukraine - that Germany kept delaying yet ultimately ended up going along with the rest in supporting Ukraine even if almost kicking and screaming - is likely what will happen now.

PS: Actually the more I thought about this the more I came to agree that most German politicians would rather just dump the whole affair and have Ukraine accept the loss of territory to Russia. I disagree that it applies to the rest of European politicians, but it does make a lot of sense for that to be the case for German politicians given how many of their top politicians Russia was paying (such as an old Chancellor who was working for Gasprom), how much they fund some of Germany's political parties, given the - as you pointed out - state of their Economy, and the History of repeated hesitance and delaying of the German politicians compared to the rest of European politicians when it came to supporting Ukraine for pretty much the whole of the last 2 years.