wealthier people won't just "try this" they will spend far more of their time on Facebook if any of the poorer people they know or do business with are only on

wealthier people won't just "try this" they will spend far more of their time on Facebook if any of the poorer people they know or do business with are only on Facebook. That's the whole point. Network effects mean that if you get a critical mass of people on Facebook (and especially nowhere else), then people who have a choice to be elsewhere still have to go to Facebook to reach those people who are there.