Basically everyone gets energy from being around good company regardless if you are introverted or extroverted. Just that if you spend more than you gain from it then it feels as if you lose energy. However if an introverted person is around people they are comfortable with and don't have to spend effort to get to know then they too go positive just as you described here.

> I don’t think they’re lazy or don’t care about people

Nobody said that, they just invest less doesn't mean that they are fundamentally different.