If you want to prove Madskillz wrong, it is very simple. Just show him the attach rates.
PS3 LTD: 11.42M Software sold last week: 1.34M, 1.34/11.42=0.118 or 1 in 8.4 gamers bought a game for there PS3 last week.
360 LTD: 17.98M Software sold last week: 1.54M, 1.54/17.98=0.0857 or 1 in 11.7 gamers bought a game for there 360 last week.
The PS3 has a better attach rate, this is because of the smaller user base and GT5:P release in Europe skewing the results in favour of the PS3 a bit. Conclusion, people buy the PS3 for the games just as much as people buy the 360 for the games.