I have been playing this game for over 10 years and i'm STILL having issues accumulating enough coins to make expansions. The Coral Castle storyline truly messed my coin count and I don't seem to have ever recovered from it (and I played it live in 2017!) I have roughly 40 plots to expand to (orange and red on the map in the Expansion thread) just around the original main gameplay area and that alone is over 55 MILLION coins. Not including any other expansions on Audra, in the Marshland, where the gnome mine is, or on the far left of my kingdom where I have the Coral Castle (and associated droppers) stored.
I play nearly every day and just collecting from my coin buildings alone take over 80 energy, on top of gameplay and trying to complete open goals. It just seems so impossible!
I'd appreciate any and all coin accumulation tips you may have.