Technically there isn’t going to be too much RAM for your system unless you have bought more than the motherboard can handle. As mentioned, 8GB of RAM is great for gaming as many, if not all, games will run well at this RAM capacity. While going for more than 8GB is not a waste of your investment, it may be a while until it is fully utilized (depending on what you use your PC for).
There are specific cases for 16GB of RAM and higher being ideal for gamers. For gamers that also create content, stream, or even play music in the background, higher capacity RAM kits are a great addition. Video editors and 3D modelers wouled undoubtedly see a benefit to higher capacity RAM, such as 16GB and more.
Applications like Google Chrome can require a decent amount of memory to run everything smoothly at the same time. Having a bit of headroom for applications like this will give you the best chance of avoiding any issues/ crashes.So, if you are an avid gamer who casually streams games, 16GB of RAM is going to be the best option.
For casual and hardcore gamers that don’t use the PC for much more than gaming, 8GB of adequately fast RAM should suffice.