Eh, you aren’t really spending 30 bucks on the coffee though.
You’re spending .0002 bitcoin.
What that means to you may be something different to someone else. It’s barter, essentially.
Worth whatever the people think it’s worth.
I had a website. I could offer to accept payment in bitcoin. That caused me no more risk than accepting VISA. It all ended up as dollars in my account 3 days later.
I wouldn’t ever buy one. I continue to think it’s a scam. BUT, for the time being...merchants can capitalize on the exchange and take their payment in coin of the realm.
Think it through. Say a cup of coffee costs $X. At today's exchange rate that's Y BTC. If the "value" of a BTC now doubles that same Y BTC can be exchanged for $2X, so you effectively paid double for your coffee, because coffee is not priced in BTC. Bitcoin, by design, is a deflationary vehicle because the quantity of BTC is fixed. So the more it is adopted the higher its "price" has to rise, which means you never want to spend it.
Suppose your salary was paid in BTC. Each year your salary would be reduced because the next year's BTC is "worth" much more than this year's, and your actual salary isn't going to double each year. Your incentive is to save every BTC you earn, not spend it. For the same reason, you'd never borrow BTC because the effective "interest rate" would be astronomical. Would you try to buy a house today using a "payday loan"?
So now you have a "currency" that nobody wants to actually spend, and a nonexistent credit market. How does an economy operate like that? Economists will tell you that deflation is much more destructive than inflation. Ideally a currency should be perfectly stable, which is something BTC can never be, by design. Hence BTC can never be an actual viable currency. It's a pure speculative instrument.
Today's cryptocurrencies also assume they cannot be forged, but their security is based on mathematically hard problems that are assumed will remain hard forever. The rate of progress in quantum computing doesn't bode well for that assumption. At some point, the entire structure is subject to collapse, which again makes it completely unsuitable as a viable currency.