1. You can predict the reliability of your proxy
Since you are the owner of the proxy, you are aware of any technical issues that your proxy has to address. You can analyze the amount of bandwidth that your proxy site is using and you can come up with ways on how to set up your proxy so that it uses less of the server resources. As the administrator, you have a proxy that is ready to use when you need it.
2. You can earn some income through advertisements, referrals and membership
This is what most free proxy administrators do. If you have been using third-party proxy services for some time, you will notice that many of them have advertisements. There are some that sell banner space, while others use Google AdSense as their source of revenue. Some free proxies are also membership sites that offer more features if you get an account or join their mailing list.
You can also do those with your free proxy. That way, you can also get some income while investing time and money in maintaining the proxy.
3. It is free – well, almost
Initially, you will have to spend some cash for getting the domain and the hosting. You might also have to pay for the proxy script. But once everything is up and running, it wouldn’t cost you so much. In fact, if you already have your own hosting account, then (if your web host supports it) you can just add the proxy.