I did it for two reasons. Cycling is one of the things I enjoy a lot. I built up my dream bike based ona mixture of lightness and durability. It's something I want to ride every day when I can and not something to take out only whe the conditions are perfect. The second reason is I feel motivated to ride longer, harder, and faster because I made the investment. I want to become the kind of rider that warrants the bike.
In terms of insurance, I never even thought about it. I don't see the need. I keep the bike in my garage. When I ride other than from home, I put it on the roof rack and more commonly in the back of my Jeep.