Sorry to sound ignorant, but I genuinely donāt understand what Putin could stand to gain from invading Ukraine. Can you shed any light on the subject?
He doesn't. That's the super frustrating part of this mess. Everyone with an ounce of knowledge about European-Russian international relations is scratching their heads going "what is this, and why now? He gains nothing."
A lot of people will blame this on NATO expansion concerns, but the truth is that NATO expansion has been a "concern" for years and nothing like this has ever happened (even the Invasion of Crimea in 2014 wasn't near the level of what's happening right now). Putin's not afraid of NATO; NATO's largely proved to be 'all bark and no bite' in response to repeated acts of Russian aggression since 2008. He's gotten bolder and bolder and tried to assassinate an ex-FSB agent-turned British spy on UK soil less than 5 years ago, for god's sake. Also, Ukraine's not even in NATO; if he wanted to be aggressive on that front, he'd go bother the Baltic states. If people think he's scared of NATO, they're not paying attention.
There's basically two answers that I can give that might make some sense:
Ukraine has a lot of natural gas and mineral resource reserves, and he could be trying to control them. He could also be theoretically be trying to gain control of Ukraine's southern ports, since having access to those waters been an everlasting Russian NatSec and trading issue for say......the last thousand years. That doesn't really make much sense considering the circumstances, though, especially since Russia already controls Crimea.
He's an ex-KGB officer whose pride was mortally devastated by the fall of the USSR and has been longing to recreate what was lost for thirty years. He wants to reinstate the Russian Empire (or at least the USSR as he remembers it), and he's tired of waiting for these silly little democracies on his western border to give up their "teenage rebellion phase" and come home to Mother Russia. It would explain Russia's ongoing attempts to undermine democracy worldwide (including in the US in 2016) and their cyberwarfare against the US and UK too, since a Divided West is a Weak West and a Weak West is a Beatable West. It's Russian imperialism at its finest, led by a man emboldened by his hurt ego, the West's appeasement tactics re: Crimea, repeated lack of consequences for Russia's aggressiveness on the world stage, and four years of Trump sucking up to him.
That's.....unfortunately all I've got. #2 makes total sense and is absolutely what's happening, but the way he's going about it and his actions over the past few weeks are really baffling me, because it's a completely irrational and politically stupid way to actually achieve his intended purpose of re-consolidating the former Soviet Bloc (and make no mistake because that is his purpose, which anyone who's ever listened to one of his annual speeches at the Kremlin would know).
So the only answer I really have for you is "he's finally gotten impatient waiting to re-draw the map of Europe by force and thinks he can escape permanent consequences by doing so now," even if it still doesn't truly explain what the fuck he thinks he's doing by invading Ukraine now with the strategy he appears to be using.