bitcoin is maintained by core developers, would Bitcoin die a natural death if the developers no longer exist? Or if they stop maintaining/developing/upgrading the system?
Yes I agree with you but it is not only the developers and miners. People make something for sale in the market but if there is no customers then the production of that thing is totally lose. Therefore I think people all over the world also the main cause who have kept bitcoin alive.
If the investment becomes zero today, the death of bitcoin occurs the same day. So I think that all the people who are involved in bitcoin keep bitcoin alive.