Whilst facebook is struggling to acquire new users, its key strength is that core users are the original social media users, now aged 40+ with the biggest incomes and are the main purchase decision maker in their household. People aged below 30 in western markets barely use the platform, so it will soon just become a echo chamber HateLand full of Trump and Brexit supporters. Instagram users (moreso TikTok) are poorer and with far less spendable income, WhatsApp is used to improve targeting.
WARC estimate that its
hitting 1% of Facebook's ad income, the main issue being that so much of facebook ad revenue comes from SME's. However, now marketing leaders like Unilever, Coca Cola, Starbucks have gotten on board, the situation will get more intense as the election approaches. Expect lots of consumer led #campaigns encouraging other brands to boycott.
The biggest issue for facebook is perception. Already many anti Trump or anti racist people associate Zuckerberg with Alt Right; if that continues for much longer, facebook's brand equity will become more toxic than during Cambridge Analytica scandal, which it had only just recovered from.