How do i word it better so that its clearer, so people wont ask the question?
I can't think of a non-awful phrasing that solves the issue. (I thought maybe let them be Treasure cards and disallow playing them in your buy phase, but then you get into trouble when something allows you to play Treasures in your Action phase, so I don't think that's a good idea.) Seems like an interaction you just have to clarify explicitly.
Card is interesting for sure! (I didn't upvote bc of phrasing errors.) I would rephrase, even if it doesn't solve the Capitalism issue, into
+1 Card
+2 Actions
For the rest of this turn, Coppers are Action cards with "+1 Card, +1$". (They are no longer Treasure cards.)
(+cards always comes before +actions, and the "with" phrasing is from inheritance.)
How come this doesnt have +1 buy?
Well I don't think there's a rule that cards that produce a lot of $ must give you a buy. It would be much stronger if it had a buy, but stronger isn't better!
This feels like it's strong enough to be bought reasonably often without the buy (like mb one of three games), and if that's true, it's just a question of how strong you want the card to be. For sth that nukes other cards and just makes them into $, having a weaker effect seems preferable to me.
Also I kinda like that midas can only make money and nothing else