There may be an analogy here but I think you are just introducing confusion by trying to equate ad revenues with "taxes" and customer churn with "emigration".

There may be an analogy here but I think you are just introducing confusion by trying to equate ad revenues with "taxes" and customer churn with "emigration". Facebook's business practices aren't a "monopoly" in any usual sense of the word and so once again it is just making it difficult to discuss the associated concerns/problems by expanding the meaning of "monopoly".