I bought mine for various reasons. I was in the market for a fun/toy car. The boxster was one of many cars I considered. I test drove a lot of sporty cars - includeing the Z, the S2000, the RX8, the EVO X, etc etc.
I bought my car from my dad - and the reason I was looking at the boxster among the other cars, was that after borrowing his car a handful of times - I honestly felt it was the most fun car I had ever driven. The combination of the handling and the top down experience made it so much fun.
I actually got a chance to drive my brother in law's 996 Carrera before I ended up buying my dad's boxster from him. I was expecting to LOVE it even more than the boxster - mostly because I assumed that the bigger/more expensive 911 must be "better". Well it was faster, but I honestly didn't think it was as fun to drive. It clearly is the more prestigious of the two cars - and if i was trying to impress someone, or wanted to roll up to a fancy hotel/restaurant and impress total strangers - I'd take the 911. If I was going out for a fun drive on a nice sunny day - I'd take the boxster every time.
My dad eventually decided to sell his car. I considered the S2000 and RX8, but ultimately, went for the boxster. I wanted a drop top and the S2000 was too buzzy/loud and unrefined. I accepted that the boxster would be more $$ to maintain - but I bought this car for fun not to be practical and rational.
The 911 is a great looking car and if I won the lotto tomorrow I think I'd buy a 911 turbo or GT3 - hell I'd buy both!
But for a guy like me who is married, has kids, has a budget - the boxster is a great car.
No 911 envy here. Although I'd glady own/drive one!! I just don't lust after one or feel like I had to "settle" for a boxster.