dave-c
Virgin didn't do it - they bought it from Telewest and NTL, who did it because at the time there was very little competition for broadband.
Don't forget they installed broadband, phone and cable television a good few years ago when there was very little choice. Cable tv was a real novelty and broadband was in its infancy. Now everything has changed - as well as huge competition with broadband there is a lot of competition with the television too - Sky, Freeview, Freesat and internet tv. Mobile phones are cheaper than ever.
For another company to make that huge investment would be a massive gamble .