Russia is not the Russian Empire, or the Soviet Union. By percentage wise Ukraine has gobbled up parts of Romania, parts of Poland and Russia, and from 700 years ago when it didn't even exist, it has grown 1000% or more:
By comparison heres Russia:
Russia has given more territory away than the entire European Union, moreover the history of Russian territory shows nothing of your nonsensical Expansionist Trope, quite the contrary.
RE: I have a not-so-crazy conspiracy theory (concerning how Russia manages its "youth bulge" problem)