The biggest issue that you'll run in to with multiplayer servers will mostly be internet related. Games are very demanding (ARK included) on internet connections and most residential connections will have latency issues due to ISPs throttling connections on residential lines. Even small business internet connections aren't ideal for hosting large games at any length.
With all of that said, yeah, you could probably host your own server on your own internet connection for you and like 10-15 friends. The more action heavy the game is, the less you can host before the latency and overhead become an issue. Action heavy titles (like sports titles or first-person shooters) are super latency sensitive and each player exponentially adds to the requirements needed for running a smooth game.
As a multiplayer game developer, bandwidth and latency are usually the forefront in my mind. Tech and electricity aren't as "limited" as internet usually is and about 75% of all customer service issues are dealing with internet. I can't tell you how many times people with terrible internet connections have told me to "fix your servers" in the games I worked on, when the servers are just fine and their ISP has started throttling them because they use too much bandwidth/data.
In any case, the games you mentioned aren't as action heavy as something like Deathmatches or, in my case, car soccer, so you can still have a narsty internet connection and it'll be fine for you and your 6 friends. The moment you start hosting huge raids or groups is when you'll start feeling the pinch. You'll also feel the pinch in games where the server controls the physics. The amount of data that the server will push is insane and it's replicated across all the clients to make sure the physics data is exact to each client. This is where exponential clients will actually kill an internet connection, speaking from experience.