Important to notice that whole game is designed this way that every building gives multiple options for development. There is a lot of market speculation, even reading @dcitygame posts about updates and guessing which building will be required for something might be very profitable. Generally in nft business close following of the project you bought in is quite important, you can buy nfts to check it after year and realize that you missed 5 drops, and nfts are 80% cheaper.

Another thing is scalling with time(it's slow game) and how users at beginning felt that they have all the buildings didn't know how to use it. Then with closed editions, and combined buildings you actually see rarity, and scarcity.