[repolfx]

Well, charging for it. Yes, they'd lose a big chunk of the userbase who value it a little bit but not really. But is it worth, say, $1/year to most users? Probably! And Reddit has 330 million users. Even if your conversion rate at that price is only 10% you should be able to run it for $33 million / year - it deals primarily with text, the software is relatively stable, it doesn't advertise. I suspect Reddit could be run very cheaply.