But I can't use my gold to buy pc-parts on my eshop.
Great answer to OP's question. Bitcoin isn't currency alone, it's an unique payment method. What kind of payment method gold is? Give thing hand in hand. But what is bitcoin? P2P online transaction which is included in blockchain, protects your privacy and you fully own it, no one can steal it without knowing keys while someone can steal your golds even from your hands and pocket. Years doesn't matter, we were different 1000 years ago, now we are far developed from that era and can say the same on bitcoin, it's far developed payment method and currency compared to gold.
because bitcoin is a very flexible asset and even though gold and bitcoin have very far different years, it doesn't mean that bitcoin has no benefits in many sectors. currently bitcoin has grown considerably and you can complete transactions using bitcoin quickly and about gold we cannot make it that way because gold is only an investment asset that is only to be hold for the long term