The most basic definition of a tycoon game is one where the player's ultimate goal is earning a lot of money. And generally the player can't earn the money by killing monsters or stealing from NPCs; the player has to earn money by producing and selling something. Usually there's some strategy: the player may choose which project to invest their time and starting capital into for greatest profit. Or the player may choose which upgrades to purchase or build to increase their production capacity, efficiency, project options, etc. And usually the player climbs a tech tree and amasses infrastructure and abilities over the course of the game. Story-wise the player is usually pursuing an ambition to become the best in the world at their profession, in a way directly parallel to the typical MMORPG story goal of becoming the best warrior in the world.
Condensing that, here's a definition: A tycoon game is a game where the player makes strategic choices about investing time, money, and resources into producing and selling something to an NPC market for a profit, as well as building up infrastructure and abilities to become better at this cycle of production and sales.
Now, my question is, can you have a tycoon game about something other than money? For example there are a few crafting-central MMOs now, and one of their end goals is to own a palatial estate (by building up from your start as a penniless, homeless adventurer who doesn't know anything about crafting). This palace is a natural product of learning all crafting techniques and carrying out crafting quests, ultimately becoming "the best craftsman in the world" (or at least equally the best as other players who reach the same mastery). Sales are not the point of this kind of crafting, and it may not be possible at all to sell things to NPCs, though trading to other players is a social activity and sort of like a minigame. Can you call this kind of game a tycoon game? Could you call it a crafting tycoon, or an estate tycoon (property tycoon, building tycoon, profession tycoon, whatever)? Or would that kind of term confuse people by bringing to mind a different kind of game where the player was making money by selling the crafting, property, building(s), profession, or whatever term was used in the phrase "X tycoon game"?