These are just statements that makes these people being discussed in society like we all are doing. If he is so interested in such then why not providing easy jobs for everyone through facebook i mean there are multiple jobs like freelancing marketing advertising etc. If he do so then he wont be rich and wont be in top10 richest worldwide and then who will know him?? so these are just statements for discussion not for implementation.
He "only" has a few billion dollars.
For comparison, if we took all the money in the world and divided it up equally among all the people, everyone would have about $9000 USD in their pockets.
Zuckerberg only has a laughably tiny fraction of the world's money supply, thus he wouldn't even be able to provide a few dollars to every person.
Basic income is something that has to be funded through central banking or other structural means. It's not something that any private or corporate entity or collection thereof could possibly ever afford.