Deck Building Requirements

I realize this is highly subjective.

To enjoy exploring popular deck builds, how many expansions do you feel like you need? I’m just learning the game and already I enjoy deck building. I see on ArkhamDB that many of the popular decks require 10+ decks/expansions?

In your opinion, what is the real core set of expansions? I was thinking the revised core set and first two campaign+investigator sets would be enough to keep busy indefinitely, but the deck building requirements seem extensive. For you, is it all in or do you draw a line?