He might be "resigning", but he's probably still going to keep his €7957 a month salary as an MEP until the UK eventually finalise their withdrawal from the EU. In spite of the fact he hardly ever turns up to vote for anything. Clearly he hates the establishment so much that he's willing to keep sponging money out of the very institution he claims to despise.
He will resign because Nigel Farage has made so much money on going short, he need never work again.