I've recently passed the 5 year mark on Reddit and watched my on-site time drop to minutes a week over the last few months.

Not sure why, unlike some people who complain, and have been there less time, the quality of submissions and comments is not really any worse than it has ever been. But then it has always just been a time wasting diversion. It did manage to kill my use of slashdot 5 years back. Maybe my Reddit time has been killed by techmeme/river.