Bitcoin is valuable because there are people who want to buy it. This value is derived from Bitcoin's blockchain being a publicly visible decentralized and immutable ledger with the utmost security of available options.
The game theory at play with the mining aspect has also led to massive investment. This investment was made by major players globally and they will protect their investment by purchasing the underlying currency if needed. This leads to a feedback loop of sorts that will continue to cause the price to rise until one day there has been so much investment made that needs to be recouped, that it surpasses the funds available to prop up the underlying currency, and it crashes. No idea if this will happen in 5 years, 25 years, or 150 years, but it seems inevitable from a long term view. Technology will continue to present better solutions to the problems that Bitcoin fixes, and at some point I believe that will overcome the network and first mover effects. Until then, dance while the music is playing.
yes bitcoin can lose its top position for many reasons in the future
a. devs change the rules of the 2,099,999,997,690,000(sats) shareable units to become 1000x more (yep they're thinking about doing this)
(i) not only will it break the shareable unit limit. (under the guise that 100,000,000,000 shareable units is still 1btc)
(ii) not only will it extend the halving timescale by another 40 years
(iii) but it will make a 6.25 legacy value (62500000 units). appear as a different amount unless more cludgy code is added to separate/convert
b. mining reward/transaction income plateau where by other altcoins then take on the asics that are not profiting
(i) not only dropping bitcoins difficulty on the exodus
(ii) not only losing the underlying value(cost of coin maintenance)
c. offchain solutions exodus full node users in preference for non-maintaining bitcoin because they are busy using altnet lite wallets instead
(i) not only centralising the lesser collective of full nodes to only merchants
(ii) not only making users not care about securing the backbone of the network
(iii) not only putting increased bandwidth pressure on the remaining fullnodes to service the remaining network full nodes