In general you should work on your strengths because those are the items that will stand out. But there are minimum knowledge requirements in other areas that can hold you back. Figure out what's holding you back from interview feedback cycle.
Being good at one specific thing makes it easier to get a job vs being a little bit good at everything. But it limits you.
The social stuff can be positive or negative. Not going to the christmas party is better than going getting drunk and offending someone. I stopped going to these things because little good can come out of them and a lot of bad. Risk management. In general it's safer not to interact much with others at work or voice political or religious opinions. I think these days your non-social approach might work out better.