However, I don't think your figure of 3.4bn USD is correct.
http://domainincite.com/20121-icann-ups-new-gtld-revenue-for...
https://www.icann.org/en/system/files/files/adopted-opplan-b...
So, I think it's the registrars (GoDaddy, etc.) that get this money, not ICANN. Blake Irvin (CEO, GoDaddy) made 1.9 million in 2015 (with a turnover beyond 1 billion).