Well not quite but close. I'm holding a hard disk that has ALL of Wikipedia's text in 10 different languages.
Yes you can download all of Wikipedia and yes it can easily fit in a hard drive. Isn't that amazing? Text is incredibly dense compared to images and video. Around 22 GiB for English Wikipedia alone and 56 GiB for the 10 languages I downloaded.
I also have all of Wiktionary in the same hard drive. It's around 16.4 GiB.