He seriously underestimates how many songs there are if he thinks he has a remote chance at collecting every song ever recorded. I own about 90 DVDs worth of MP3s, mostly electronic songs (jungle, trance, house, etc), and i'd say it represents maybe 3% of all the electronic songs ever recorded, at the most.
There is probably 5000 new songs recorded a day. There is no way in hell he can get close to it. His present collection of 900,000 MP3s is probably about 1% of the songs out there IMO.