We could say digital gold is btc alternatives. But bitcoin has no physical asset and consist only of digital but has immensely got some fair value. If you would noticed both are limited in supply like btc max supply only to 21million while gold is a naturally occuring mineral which also can be conserved as thr process of producing is limited to countries potential resources. If this in the future got depleted more, imagine its price value due to scarce. The only difference of two are its use case which gold preserve more advantages since it can backed up some currency such as US unlike btc which still got some issues.