The filter, exactly. You will probably only read ~5000 books in your lifetime so targeting the best of the best will maximise your enjoyment. Of course you should pursue an author/series/subject that you particularly enjoy. It's also nice to read books that friends recommend so that you can share the experience with them.
I tried to read as many books as possible for a period of time between getting an ereader and huge book dumps. I found I could read a book every 3 days on average. Keeping that pace you could read 100 books a year. People can't keep up that pace. Of the people who read if they finish more than 5 books it would be amazing.
You have periods where you read more like in school. Most people will not have read 50 books by the time they have finished school. Books on tape could increase the numbers.
Most people will have read 5 or less books. Those who do read will probably average 54. To get to 500 would be amazing.
To get to 5,000 would take you 50 years of reading every second you could outside of work.
The correct number is somewhere between yours. I remember encountering the number 3,000 for serious readers at some point when I was in my twenties and being rather depressed at how low it is. Goodreads is my sole social network these days and it's interesting to see the range of numbers that my friends pick for their challenge goal each year from as low as single digits to one friend who routinely reads 200+ books a year. Since I've started tracking my reading about 26 years ago (probably around the time that I encountered that 3,000 books number), I've read 1,840 books (with my annual totals varying from a low of 27 to a high of 129). Probably the most important thing towards this was something my Latin professor told us, saying that if you read just ten pages just for yourself each night before you go to bed, that becomes 3,650 pages over the course of the year which is nearly the entirety of À la recherche du temps perdu. It also helps that I've done things like commute by public transportation (extra reading time) and I value reading as a means of entertainment.
