It’s tied to energy, the value is the wattage used for the reward and the network will use more and more energy and the reward will become less per block over time.
Discussion
You should own and save in bitcoin for the two worlds we will have in 20+ years
Physical: In 20 years a block reward will be less bitcoin and exponentially more watts will be used to mine it. This is important because the main input cost to anything physical is energy.
Digital: Technologies using bitcoin base layer and lightning will allow people to subject others to physical constraints over a digital space. This will be used via divisible units of bitcoin. Lightning has not been properly thought of as a way to subject the implications of natural law to people over the internet but it will give people the ability to choose that whenever they want/need to.
A proof of work scarce digital store of value that no one controls would be a winner take all game. There will not be other proof of works with significant portions of global use. It is inevitable that it would become a way to escape being unbanked, then mild inflation protection, then used in cross boarder settlement, then used for sovereign individuals to subject other actors to natural law in a digital space. Right now the transition from unbanked to being used for escape from just mild inflation is just starting.
