If Russia truly wanted to conquer all of Ukraine, they would have made their move in 2014, when the Ukrainian army was far weaker and the front far less fortified. Instead, they stopped at Crimea, and provided only limited support to the breakaway provinces in the Donbas. (To this day, many hardline Russian nationalists resent Putin for this! They think he was "too soft")
Putin invaded in 2022 because he believed his hand had been forced. It wasn't, he was (and is) delusional and wrong, but there is every reason to think that he really believed it.
If Russia truly wanted to conquer all of Ukraine, they would have made their move in 2014, when the Ukrainian army was far weaker and the front far less fortified. Instead, they stopped at Crimea, and provided only limited support to the breakaway provinces in the Donbas. (To this day, many hardline Russian nationalists resent Putin for this! They think he was "too soft")
Putin invaded in 2022 because he believed his hand had been forced. It wasn't, he was (and is) delusional and wrong, but there is every reason to think that he really believed it.