Are unprinted photo files worth keeping?

I've been sorting through and purging 4 years worth of personal photos in the past few weeks, tagged around 200-250 per year as favorites, and printed them as 4x6s.

Now that I have all this printing done I wonder;

Is it worth keeping all these files, if they weren't important enough to print?

I've always purged photos when I've moved some over to my laptop, but about 2,000-3,000 personal photos from each year still sit on my hard drive.

How long will they survive on my hard drive without going corrupt? How many places would I have to back everything up at, to not have to worry about them?

The thought of deleting the files that weren't print-worthy is tempting. It would clear out a lot of clutter and free up storage space on my hard drives.

I might end up tagging and printing a fresh batch of photos before I purge everything else off of my hard drives. This way I will not only clear space, but make it easier on myself when I go through memories. How many pictures of Nova catching a ball on the beach do I really need?

Ok, I need many. But surely not as many?