HATRED comes about from fear.
... as does a need for CONTROL. The Church of COVID (as well as the Church of Global Warming) is a prime example of such behavior.
This is how I would consider encapsulating the leftist ideology:
fear ---> need for control ---> hatred
1) At the very core of every leftist, you will discover the presence of
FEAR. (E.g. fear that if you live your life in a manner that I dislike, then it might negatively affect ME... fear that if you get a job, then there won't be any jobs left for ME... fear that if you make a lot of money, then there won't be any money left for ME, etc. etc.) ... It is this sort of fear (however it might manifest) that leads into #2...
2) So long as the aforementioned FEAR is present, it causes leftists to seek out ways to create safeguards against anything/everything that they happen to fear. Thus, leftists seek
CONTROL over others in order to alleviate their fears.
However, no matter how much the leftist tries, the leftist just plain cannot control the actions of other people around them. Some people are just plain not going to wear a stupid face diaper that doesn't work against viruses, or choose not to get stupid mRNA jabs that don't stop anyone from getting sick, no matter how much any leftist happens to fear COVID. It is this sort of need for CONTROL, and the lack of being able to obtain it, that leads into #3...
3) So long as leftists are filled with FEAR (#1), and so long as leftists lack the CONTROL over others that they so desperately NEED (#2), leftists will inevitably be very angry individuals, filled with all sorts of
HATRED towards the very same people who they cannot control... the people who aren't filled with fear like they are... the people who don't need the same control over others that they need... the people who aren't miserable saps like they are. This is the manifestation of leftists lashing out at the world, blaming anyone and everyone else but themselves for their own fears.
This (the presence of fear, and the subsequent need for control to alleviate said fear) is where the leftist's hatred/meanness comes from.