Obviously the local theatre benefits your own community, but if you live there then you are also benefiting yourself (via status and seeing plays), which seems less than altruistically pure, even if you could only build 1 theatre in Africa.

You know a lot better what a theater could bring to a neighborhood you know well.

And then, there's the question of if altruism itself is most efficient at helping others. Some would argue that helping oneself but where it benefits others as well, win/win situations, in practice produces better outcomes. The idea of self-sacrifice, or having to lose or risk something personal to help others sounds noble, but might not be most effective.