While I agree that networking is a vital part of staying in touch for any new position, should you happen to be looking for a new one, there are other aspects to networking.
For those of us who are comfortable in our positions and choose NOT to look for a new position, networking with your peers has other values. You may learn about a new technology that a business associate is working on that could help your company. You may learn that Company XYZ is offering discounts on hardware / software that you were not aware of. You may hear that someone is having difficulties and you could end up mentoring that individual with your experience, or point that individual to someone you know that solved that particular issue. You may learn that a competitor has lost a contract and there is a business opportunity to be followed up on. And, there is the opportunity to get out of the office and mingle, learn new stuff, and see how the rest of your peers are doing. Perhaps to even be thankful you have a secure position.