Like many things, it's an all of the above strategy. People should invest their time, money, and effort in fixing the things they can have the biggest on. For instance, I may support a lot of causes, and within each cause I may support a lot of tactics -- but I invest in the tactics and causes where I can make a difference.
If each of us takes that approach, we'll cover all our bases.
For me, that means educating the non-technical on IP law, educating fellow WASPs on privilege blindness, and educating employers on how to write job descriptions that don't select for "ninjas" or "gurus" with egos the size of Mars (thereby scaring away most underrepresented people).
What's most accessible to you?