Unfortunately these days if you decide to open a server you are going to get ddosed. The bigger your server is the bigger target you are. The only option is to move to a ddos protected network. Using software protection, external hardware protection (like firebox or even cisco) are not enough. Upgrading your connection to 1gbps is not going to help it is only going to cost you more. If the attacker is already hitting you with a large scale attack he is going to be able to kill your 1gbps right up to 10gbit/s 10mil/pps.
Especially with large servers these guys are making money or at least trying to. You get ddosed and than are contacted saying they xxxx amount of $$ to stop the attack.
It sucks that the community has come to that. So if you are going to start a server seriously think about going with people like staminus, blacklotus, gigenet, or dragonara. These people specialize in protecting you from ddos attacks. Is it more expensive...ofc. But you have to do it if you are going to have a serious server. Do your research on those companies 1 may not be as suitable for you as the other. For example one of Dragonaras main partners is Cogent which is not great quality bandwidth and the routing for europeans is horrible.
Do your research!!