Instead, what they're doing here is encoding the data contained in a torrent file as valid image data. I'm not sure exactly what technique they're using, but the process is essentially analogous (though surely more complex) to treating each bit as a black/white pixel indicator. Given some agreed upon dimensions for the image (either width or height, doesn't matter which) this gives you a black and white bitmap which could then be encoded as a png.
Clearly what they are doing is more complex since their images are color (and they may be relying on specifics of the way png images are formatted), but the basic idea is the same.
But when you graduate, marry, and have kids, will you have the money to keep five PCs upgraded, one for you, your spouse, and each of your children?
I'm not quite sure why you keep bringing up this notion of having five game capable PCs in a single house. None of the LAN parties I've been a part of (except those in the CS lab at school) involved having computers already present. Everyone brought their own. So the question of whether I would have enough money to keep five PCs in top gaming condition (the answer is yes, by the way) is irrelevant. I any case I would always have a PC for my own dedicated use and 1+ for anyone else I lived with.
Machines take me by surprise with great frequency. - Alan Turing