Crowley had always known that he would be around when the world ended, because he was immortal and wouldn’t have any alternative. But he hoped it was a long way off.
Because he rather liked people.
It was major failing in a demon. Oh, he did his best to make their short lives miserable, because that was his job, but nothing he could think up was half as bad as the stuff they thought up themselves. They seemed to have a talent for it. It was built into the design, somehow. They were born into a world that was against them in a thousand little ways, and then devoted most of their energies to making it worse. Over the years Crowley had found it increasingly difficult to find anything demonic to do which showed up against the natural background of generalized nastiness. There had been times, over the past millennium, when he’d felt like sending a message back Below saying, Look we may as well give up right now, we might as well shut down Dis and Pandemonium and everywhere and move up here, there’s nothing we can do to them that they don’t do to themselves and they do things we’ve never even thought of, often involving electrodes. They’ve got what we lack. They’ve got imagination. And electricity, of course.
One of them had written it, hadn’t he … “Hell is empty, and all the devils are here.”

Terry Pratchett (1948-2015) English author

Good Omens, 2. “Eleven Years Ago” (1990) [with Neil Gaiman]
    (Source)

The quote is from Shakespeare, The Tempest.