We race because its more darn fun than anything else you can legally do in public.
So now you are drifting along in your new boat, head on the gunwale, feet on the centerboard trunk, tiller over your shoulder, and not a care in the world. And then, beside you, appears another boat. You both glide along side by side, talking, and then you notice he is a little bit faster. You pull in the sail a bit to catch up. Now he does the same to catch up with you. Before long, you are both hanging over the side, trying to coax every last bit of speed out of the boat to be the first to the dam. An interesting experience, and you decide to enter a regular race.
Now its Sunday afternoon. 5 minutes to the start. You and other boats just like you are moving back and forth, closing in on each other and the line, confusing to viewers, but with a rhythm and pattern like a dance. 1 minute to go. Boats seem everywhere. Closer and faster. A few shouts. 10 seconds. Here comes the starting line. Will we be too soon? 5! 4! 3! 2! Bang! We're off!
The confused milling is now a straight line of boats moving parallel down the lake. A glance at a neighboring boat, at an approaching gust, and "Ready! Tack!" You change directions, taking advantage of the wind shift. Boats are beginning to separate. Several more tacks, and now there are several of you together, each eyeing the other, heading down the lake together. A chess game where you are one of the pieces. Do everything right, hope the others make mistakes. All your senses are focused as you try to outguess the wind and your opponents.