SciFrog:
Because Ferrari used prices hold much better, resulting in less $$ cost of ownership. Ask Nick...
That's not always true and very model specific.
Here in the UK an F430 trades at a lower percentage of original list price than a same year 997 Turbo, so the Ferrari buyer has lost more in percentage terms and far more overall $$ (or £ in our case). In fact an F430 Spyder buyer has lost more than the 997 Turbo buyer paid for his car!
Also 612 and the new FF are far worse. 612s here start below £50k used for a £200k new car, so 75%+ lost and £150k+ lost. FFs are being bought back by dealers at huge losses for the owners within the first year (tales of £100k loss in 6 months on heavily optioned cars). Different story if you bought an F40 or F50 at the right time of course!
Same with Porsche, varies massively by car. GT3 hold huge residuals, GT2 don't in comparison (2008 GT3 dropped from £80k to about £50k, GT2 from £140k to £70k) ie GT2 has lost almost the entire cost of buying a GT3!
Old Cayennes destroy money, earliest Turbos are now £10k here down from £70k+ options new, so typically £80k+ new.
Its certainly the case that Porsches massively increasing production has hit residuals compared to the past, but it varies enormously by model. It's a rare car now from any manufacturer that holds decent residuals.