Everything you have that have value is considered to be an asset, like gold ,real estate, vehicles, and others with values, bitcoin is considered to be an asset because it has value ,even if it can not be seen in physical form but only in the digital but it is still considered to be an asset because of its value.
I don't think so, in some country , bitcoin and cryptocurrencies aren't counted as a legal asset like gold, real estate as you said so that means things will become awkward for sure.