Although the number is minuscule, it still the real-world usability as a mean of payment, as someone who holds bitcoin, I'll be happy to buy a coffee using bitcoin even though it may become the most expensive coffee I've ever paid in the future when bitcoin reaches $1 million.
As time goes on, more merchants and retailers will accept bitcoin, that's what the purpose of bitcoin, to become an alternative online payment.
Everyone is free to choose whether to pay using bitcoin or fiat currency.