[this post is from Nerd Dennis Houseknecht]

Some residential clients (and even some businesses) knowingly run “open” or unsecured WiFi networks, seeing little risk in doing so. Some are happy to share their connection with neighbors.
Here is one good reason that all WiFi networks should be secured. If someone is doing something illegal that requires an internet connection, they are not likely to do it from their own network. An open network is an invitation to others to use your network – even for illegal activities. It is better to secure the network and provide the password to neighbors or others with whom you want to share.
Cybercriminals Target Small Businesses – NOT Just Larger Ones
Here is an example. Many larger businesses are beginning to understand the risks and are implementing better security controls. Unless small businesses do the same, they will become the “low-hanging fruit” that cybercriminals are always looking for.