They add a little gold for a more stronger foundation of some items like the diamonds. The same is the usage of btc but in the cryptoworld.
I want to use bitcoin to buy exactly the same stuff as fiat, hoard, partially invest, buy stuff from digital games and online purchases to stores. I will exchange it with the currency that exists in my country with the help of an exchanger and then paying to the buyer. You can keep earning wealth as well and keep spending on the same level and it gives you all the freedom you want.
for me the real usage of bitcoin is through investment and payment on different transations to estabidhment that accept bitcoin.