I discovered this term monotropism and now I can't stop thinking about it (only partly joking): https://en.wikipedia.org/wiki/Monotropism. Not saying it necessarily applies to your situation but I hope you can see why I make the connection.

> Monotropism is an individual's tendency to focus their attention on a small or singular number of interests at any time, with them neglecting or not perceiving lesser interests.

I recently also picked up Magic: The Gathering again and started playing at a local shop. Now I can't stop thinking about decks which might be fun to brew. I guess I'll see how long it lasts but I intend for it to be a long-term interest.