A game is not something you own. Its something you pay for to consume. You buy a license to it.
(You also dont own the text when you buy a book)
Just beucause in the past the software had to be distributed on a physical medium, it does not mean its like buying a butter-knife that you can pass around and sell it to the neighbors.

Its the same with a movie ticket or a trainride. You cant use it and sell it afterward to someone.
You also cant morally claim, just bacause the train or theater is empty that you can invite all your friends with your single tickets for the ride.

Of course noone knows if you sell a game CD to someone,
but this does not mean you should have the same rights
with an online distributed downloadable game.
There you only pay for your personal right to consume it.

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BTW: given the potential gameplaytime you could enjoy playing minecraft, 20€ is quite cheap.
If you spend lets say 40 hours in the game (single + multiplayer),
thats 50Cents per hour. (there are certainly people who spend weeks in the game, lets assume a normal user)

a movie in the cinema costs like 4€ per hour.

Some highend GFX singleplayer shooters cost you maybe 2€ per hour.

Many Phoneapps wont enterntain you more than 1 hour.
Thats then 99Cent per hour.


I always mentally price the games according to quality entertainment time.
This is a much better comparisson than the rough pricetag.

(Going out with a nice girl cost 40€ for the meal and 348.642€ for
the next 50 years.
)