The amount of Killie and St Johnstone I know of who now focus on English teams instead of their own is the main problem IMO.  Either that or they fall away completely.

Guilty as charged. 20 odd years season ticket a Dens park now lucky if I go once a season. My reasons are known, work and the other one.
Focus on Millwall now. I get much more enjoyment from attending their matches now.
Will always love the Dee though 🙂