I've 100% completed about 2500 of them, so I don't have a great completion rate but it's not like they're just there for show. I've probably played around 6000 total.
A very large number of them I would not have bought individually, but they came in a bundle with other games I wanted.
>>sellym+(OP)
Maybe not a great completion rate respective to the amount of games you've got but probably (surely?) with respect to other gamers! If someone asked you to pick your favourite three...?