What made fantasy/sci-fi/"geek TV" one of the main early drivers of TV-on-DVD sales?

Submitted ⁨⁨1⁩ ⁨week⁩ ago⁩ by ⁨bOt@zerobytes.monster⁩ to ⁨television@zerobytes.monster⁩

https://www.reddit.com/r/television/comments/1wreo2u/what_made_fantasyscifigeek_tv_one_of_the_main/