Try disabling any extensions you have in Chrome and see what happens to your RAM usage. If RAM usage is normalized after disabling them, start enabling them one by one to see if you can find the one(s) eating your RAM.
I’d also suggest for everybody, not just those having issues, to set it so Chrome doesn’t run when it’s closed.
Settings > Advanced > System > "Continue running background apps when Google Chrome is closed"
It’s enabled by default, disabling it will make Chrome actually stop when all tabs/windows are closed.
Testing my own Chrome I’m using 3.0 GB with eleven tabs and Steam running in the background.