No need for excessive speed, expense
I bought a 250 because I like to ride, and I like to live. I am happily married and have 2 young kids. I rode a Kawasaki for 7 years as a kid, but that's been 18 years ago. My Kawasaki experience then was pure joy; I never had a single problem with that machine after totally abusing it for 7 great years. When I sold it, I got back half of what I'd paid for it. To me, that's a great deal, both from a money perspective and from a fun perspective.
Let me mention something to the macho 600cc+ crowd. In economics, there is something called "diminishing marginal return". It basically means that, after a certain point, you start getting less and less results (i.e. riding satisfaction in this case) for your money. I paid full sticker ($3,299) for my 250 and was glad to do it (the dealer only makes about $200 on this machine anyways, at full sticker). I pay $105 per year for comprehensive insurance with a low deductible. This, along with a little bit of depreciation and lost interest on my cash, is my only expense to own this bike. I figure it all adds up to about $500/year, or $40 per month (about my cable TV bill). This is, by far, the most riding satisfaction I can get at anywhere near these prices. Period. I've got the cash on hand to go by a huge sportbike, but I don't like to waste money. I like to have fun. I can do that on a 250 Ninja as well as I can on anything else.
If I rode 8,000 miles/year or more, I might make the investment in a 600cc, but as a pleasure rider with 2 kids' college to still plan for, I'll take the 250 any day. On a pretty day on a windy country road, my $3,299 buys me all the riding fun I'll ever want or need. If you want to go 0-60 in 3 seconds and top out at 160 mph, good luck to you. I just want to ride, have fun, and come back in one piece to my family. By the way, I know a lot of these macho guys are the same ones who go out with t-shirts and shorts and no helmets. If you crash, you're going to be so messed up you'll never want to see a 750, 600, or even a 250 ever again. Not many guys (or girls) who have gone through 3 months of skin grafts ever want to sit back on a bike. I wear Draggin' Jeans, gloves, leather jacket, and a Snell-rated helmet. All of that cost me $350. My body's worth thousands of times more than that. Good luck daredevils! Pay your $7,000+ and try to cheat injury with every ride. I'll be taking in the pretty scenery on all of the country roads near my house and joyfully be obeying the speed limit.