[Jare]

Phaser is perfectly fine for that. Since you are building a game about some sort of economy that evolves, you are likely to need some graphs in your UI, I doubt Phaser has components strictly for that but it's likely that someone has done some libraries, or you can roll something simple with the 2D primitives that Phaser does support.

However, it sounds like your game is going to be more based on UI interactions (buttons, etc) than in "realtime" action, which Phaser is very strong at. If you are already comfortable with straight HTML and CSS then you might be better off building the game as a Web App, and use lots of great libraries in that realm.

Until you have the foundations of your game, I advise you to not worry about graphics and audio. There are resources like https://opengameart.org/ where you can get some material to work with so it's not just a plain and ugly looking thing. Once you prove that the game has legs (and you as its developer have legs too) then you can start looking into creating or comissioning assets.