Well, beach and money.
Putin and his financial supporting team, the oligarchs, want
more Russian beach (and God is not creating any more beach anytime soon on Russian territory).
All of the oligarchs own HUGE properties on the Crimean
beach. And they (and their friends, family) own many of the businesses supporting the vacation trade. Putin
already paid $50 billion to turn Sochi into a world class beach resort,
but there isn't much more he can do there without invading Georgia to
the south (more beach). Crimea at least has a good 'back story'
While Putin used power to become rich by extorting
money out of the oligarchs (give me lots of your money or I'll put you
in jail for tax evasion), now his power is diluted by the money
providers. He has to meet with them and do what they all jointly
demand: "Protect our money/investments". He is now one of them, no
It is NOT about expansionism! It's just about some really
rich guys protecting their toys and leisure-time property. For the very few rich guys who own Russia, this was a smart move, now completed and
protected by the newly upgraded/modernized military that Putin has been
investing in over the past decade. The reason any dictator builds up his military is
to protect the interests of himself and his supporters.
Filter everything that Russia (not Putin) does through the "What's best for the
oligarchs?" (of which Putin is now the richest) and all motivations become crystal clear.