I did the same. I founded a VPN provider[0] in my free time. It is still running, but I have at times been close to shutting it down.
Most of my code has been open the whole time and is on github[1]. Some internal tools and the website are not on github though. I went with AGPL for license. It'll make my day if someone forks my code and founds their own provider.
I operate out of Iceland and most of my clients are Icelandic. The biggest use case for my service was ISPs in Iceland charging extra for international bandwidth. By having my servers in Icelandic datacenters, I was able to provide my customers with significantly lower prices for bandwidth, thereby lowering the cost of internet for a lot of people. Considering the huge time investment that has gone into this side project, I have not made much money from it. But knowing that I helped my internet usage more affordable is something that has made this project meaningful for me.
Since I started, lots of things have changed. Some ISPs are now offering unmetered connections (this was unheard of before). Others have lowered their prices. I have heard people attributing part of these changes to me and my company.
I have not experienced DDoS attacks like you, but I have been the subject of meetings at some regulatory boards in Iceland, as well as at the monopoly behind the submarine cables[2] connecting Iceland to the world (the source of this dual-pricing schemes). One hosting provider was forced to change their core routing shortly after I starting hosting with them, to make me unable to host there. Other providers have come under preassure from this monopoly to kick me out. Like you said, you feel like your service was real -- someone with a vested interest against it was watching me.
Some time in the near future I will shut down the service. It's just time to move on to other projects and time to recognize that it's fulfilled it's usefulness. I know I will walk away from this project with a great sense of accomplishment, I am proud and happy with the work I did.
[0]: www.lokun.is