Then imagine 100k for a bitcoin. Who in their right mind would pay that?
Right, and who in their right mind would pay $39,000 for a kilogram of gold?!
Oh, wait, we don't have to buy it in kilogram units? It can be bought in smaller portions and we can use different names for those portions? But, it's still gold, right? Ok, so mayby I can spend $39 and buy a gram of gold. That works.
If bitcoin is $100,000 per bitcoin, then you will be exchanging and buying microbitcoin (µBTC). You might even use a reasonable nickname for the quantity. Call it a "Mike", or a "microbit", or a "Mic". You'll be paying $0.10 per microbitcoin. That's a very reasonable number.