i'm not (yet) using bitcoins, and I'm approaching this world as of now..
I stumbled upon some merchants that sell mining hardware (with some GH/s).. but I've yet to understand what is they gain, apart from the upfront cash.
The reason one should buy mining hardware is, if i'm not mistake, to "generate bitcoins", i.e. "generate money"; so, one expects to be able to have a return of the investment sometime in the future (i was wondering, with a 4.5 GH/s at 180$, how much time is needed?), so I guess that in some way my claim is correct (about "generating money").
But then, why the companies don't simply.. use their own hardware?