For instance, small talk. You may style yourself as someone too intellectual to be entertained by small talk, and profess to be terrible at making small talk. This is to misunderstand the value proposition of small talk, which is to establish trust and rapport with strangers before you commit to sharing any high value information. To be fair the value of social customs are often not grokked even where they are followed and are effective. But if you need a reason for everything, figure it out.
Also, confidence. This is simply a function of how positively you expect others to receive your presence/engagement. People who are quiet and taciturn in one setting will often be charismatic and open in another setting where they know the audience. Realistically appraise why others might react positively to you, and work on being able to deliver that value. The confidence will flow naturally from there.