Honestly, he wants to return Russia to it’s ‘glory days’, which means back when it was an imperial power, and they could send tanks into Hungary to crush people protesting for democracy. When Ukrainians threw out their pro-Russian president, he saw that influence he wanted slipping away.
Because the corruption was getting out of hand in the mafia state. See: the state of russian army
Or he’s just greedy
Honestly, he wants to return Russia to it’s ‘glory days’, which means back when it was an imperial power, and they could send tanks into Hungary to crush people protesting for democracy. When Ukrainians threw out their pro-Russian president, he saw that influence he wanted slipping away.