Putin remains in power because he has the support of the Russian elites. They are evil but not stupid. If there are real personal consequences to those elites because of real meaningful sanctions the Ukrainian invasion thing will go away.
The challenge is to make Russia believe that the West is not fooling around. That may well mean short term pain for the EU and especially Germany. Failure to show resolve now, however guarantees long term pain for Europe and the US. The only question is do the Western politicians have the stones to call Putins bluff ?