Ok....please enlighten us.
Dime Store Version below. Note, this is not me being judgmental about any elements of the history. To be very clear, Putin is a bad guy who fashions himself the second coming of the tsars. Moreover, nor is this me making this up out of thin air. This is a respected russian politics academic at a major university, who developed a lot more intelligence-based data than I can recall here. Note also that I'm not going to debate this any further as it detracts from the proper focus of this thread. You of course are free to do with it what you will.
1. Post cold-war (and really more specifically, post 9/11), Russians felt that they weren't really being treated as international partners who'd helped end the cold war peaceably, which didn't go over that great among a segment of leadership, i.e., Putin, that was used to being one of the poles in a bipolar world and who wanted to put that particular band back together.
2. From 2008-2014, as Putin was settled in and transitioning back and forth with Medvedev, they felt like they got more than their fare share of moralizing about free and fair russian elections from the then-secretary of state.
3. From 2014-16, like any other sane person on the face of the earth thinking about the upcoming US election, the Russians were thinking about a future 4-8 years of President Clinton. And looking at that four years, they did not like what they saw, as it was pretty obvious to them that the prospect of 'partnership' was D-E-A-D dead.
4. So when faced with a bowl of lemons, they sought to at least try make some lemonade via social media disinformation. Critically here, when you look at the social media campaign and investment they undertook, two factors are important: (i) the primary substantive thrust of their activity was "sowing discord"; and (ii) at the time of their (really shockingly very minimal) investment in the initiative via trolling farms, etc., no person in their right mind expected Donald Trump to be the R nominee for President, let alone elected president, as he was below 5% in the R-primary polls. In short, they were not so much "for" Trump as they were "against" Clinton, and the goal of the initiative was not so much to "get Trump elected" but rather to be able to say after the election, to the world, that they should ignore president clinton's moralizing as the American electoral system was no shining city on a hill in its own right, all while they tried to rebuild their international relationships going it alone.
5. So tactically, of course, what they did was a spectacular success. They got us at each other's throats, where we more or less have continued to be. And to their own surprise and everyone else's, there was no president Clinton. But strategically, the initiative was a catastrophic failure -- if there were ever a time when it became wholly politically impossible for an american president to try to reset russian-us relations, it was during the period 2016-2020. And so, they became even more isolated than ever.
6. Finally, although it is not really part of this narrative, there is that nagging little fact that Russian's excursions into Ukraine have taken place in 2014 and 2022. And I'm not talking about the coincidence of them following the Winter Olympics, which of course is no coincidence whatsoever.