Cameron was not forced out, he freely chose to leave. Interesting.
He’s a wimp, unable to handle Brexit.
When a British PM loses a vote in Parliament on an important question it’s expected they’ll resign and let somebody else in their party give it a try. Cameron is just applying this same custom to losing a national referendum. Brexit was a direct no confidence vote, much of it by grass roots Conservatives outside the London area and Southeast, and Cameron was right to understand he couldn’t lead.