@tech savvy
Because money wise, they make more. You are paying ~£30 for a PC game when you pay ~£45 for a console game (except for the Wii which is the same price as PC). You only have to sell two thirds the number of the units on consoles that are sold on PC, and you are making the same amount.
What you are doing is comparing consoles games to their PC counterparts, but forgetting games such as WoW, The Sims, Starcraft, all of your Valve games (except for orange box and CS, but even they sold more on PC than console), Guild wars etc.
When you take into account the number of copies of WoW and their 3 expansions, The Sims and all of their expansions, all of the PC exclusive RTS games, just the sales, never mind the time played on the games, destroys console sales.
To put it into perspective, WoW has 12 million subscribers (1), the vast majority of which have all expansions. As it isn't all, let's assume it is only 11 million of those have WoW + 3 expansions, and the rest have just vanilla. That is 12m copies of vanilla, 11m copies for bc, 11m copies of wotlk, 11m copies of cata. 45m units sold, not including over £100m a month from subscriptions. Compare that to Halo 3.
Halo 3 is the most sold 360 game with just over 11m units sold, and no subscription (2). It was in the top played Xbox game since release, however, WoW is consistently the most played game (3), but NOT the most sold, that title belongs to the Sims franchise (4)(5), which does NOT hold the record for fastest selling, that belongs to WoW (6). And bare in mind, in the same way you think you need a $1000 system to play PC games, which you don't, you do need all of the expansions for WoW to take full advantage, else you will have a hard time raiding, doing instances or doing PvP at end game, all you will have is more quests and some achievements, most of which you can't get.
To then say you need $1000 to build a PC capable of handling the latest and greatest games, that too is completely incorrect. There are people I play with regularly still rocking C2D's and 8600GT's that can play every game on at least medium settings. Assuming you are to build a brand new system that can play games at atleast mid settings @ 1280x1024 (the most used resolution):
CPU:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103926
Mobo:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157215
Memory:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231149
Hard Drive:
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148511
Video Card:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814500191
DVD Drive:
http://www.newegg.com/Product/Product.aspx?Item=N82E16827118031
Case:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811164094
PSU:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139017
OS:
http://www.newegg.com/Product/Product.aspx?Item=N82E16832116754
And the grand total - $436
(1):
http://us.blizzard.com/en-us/company/press/pressreleases.html?101007
(2):
http://gamrreview.vgchartz.com/sales/6964/halo-3/
(3):
http://www.xfire.com/games/wow/World_of_Warcraft/
(4):
http://news.cnet.com/8301-13772_3-9920327-52.html
(5):
http://news.cnet.com/8301-10797_3-10261044-235.html
(6):
http://us.blizzard.com/en-us/company/press/pressreleases.html?110110