>It's not like you're creating money out of thin air.
No, but money (and value) is created out of ideas, of labor, and adding value to products.
When an IPO happens, for example, and a company owner holding 50% of the company is suddenly valued at $20B, that value did not come from taking $20B from other people. It's the value of the company. It is value simply created out of thin air, that didn't exist before.
If the next day, someone prices the stock 30% higher through market forces, the owners value shoots up 30% also. That 30% increase in a single day was not taken from anyone - it is made up out of thin air.
When a craftsman buys a piece of wood for $10, crafts it such that others value it at $1000, that craftsman just added $900 of value. It might have taken a week, or might have taken 15 minutes. It's not simply some labor value per hour times hours. The amount of value is created out of thin air, but it took some labor to allow that increase to happen. The labor amount and value added is somewhat related, but varies greatly across all endeavors.
And saying the employees could have just worked somewhere else is shuffling the truth - to have somewhere to work, someone has to start a company, which often takes significant money and risk to begin with, before thousands of workers can have a stable job. That money too was created previously through invention, innovation, labor, and previous investment.