Oh no, not diamond paid trainers. If you have to build something to progress in the game it should be a given that trainers are included, not paid. The builder is terrible too that you have to pay for more builders in a building game :/
Here’s how you offer paid buildings that doesn’t seem greedy. I want to be able to paint all of my buildings pink. (Just kidding) I get to buy with diamonds, a painting hut that uses: some steel to make a paint can. I get a free dye factory to make powders to tint the paint, from a free or paid crafting hut a brush made from horse hair from my farm and timber from the planks factory and latex a little magic dust to make it sparkle, fruit from my farm to color (I have no idea how to make paint – making this all up) then send this to my painting hut to produce paint. If you don’t have enough of the ingredients you trade with players that have fruit, the free crafting hut, and the free dye factory. Then those who don’t have a painting hut, can buy paint from those who bought the painting hut and they can now paint all of their buildings pink too!
These give you other activities to do, it’s not about points or winning the game. I’m trading 1 can of royal blue paint for 5 crystal relics any takers?