Why does Bitcoin have value?

For starters, stuff has value because people consider that stuff has value. Value is subjective. Value is in the human mind, not in objetcts.

This said, if the value of bitcoin is explained as store of value, i.e. buy it now to be able to pass it on later to someone else, what made it have value before anyone was storing value in it?

Some will say that Bitcoin started to have value since the famous pizza payment.

Well, in reality, bitcoin has value since it's inception.

The first person who attributed value to it was Satoshi Nakamoto. This person attributed so much value to Bitcoin, that he invested a big amount of time and effort building the system and supporting it in the beginnings.

He did that because he saw value in it.

Some other persons saw enough value in Bitcoin as to download the code and running a miner spending time and energy in the process. You don't do this if you don't see value in what you get.

The value of the system just increase as it gets adopted by society and more and more people demands it.