How do you accumulate all this music, most I've ever had in iTunes is 100ish songs.
There are two legal ways: One just takes time. At some point I used to buy 10 CDs or so every month. Do that for twenty years, and you have about 30,000 songs. The other method: There are sources of cheap music. You can get an awful lot of classical music really cheap. For example: Bach complete works on eBay, 155 CDs for £69. That would get you from zero to 2000 songs / 8 days / 20 GB of music very quickly. And you can buy some indie music really cheap.