Why did Airbnb founders deserve X% of the shares of their company that could be worth billions of dollars? Because they made a stupid simple website to rent out

Why did Airbnb founders deserve X% of the shares of their company that could be worth billions of dollars? Because they made a stupid simple website to rent out your apartment? Same question, same answer. We live in a capitalistic world, I think it is reasonable that people try to launch for-profit ventures. Ethereum did something equivalent to a pre-mine + instant sale: they created the initial ETH supply out of thin air, and immediately sold it for BTC to investors.