Is crypto the future of payments? Well, Adyen isn't quite convinced yet.

Adyen, the European fintech giant processing payments for the likes of Facebook, Netflix, and Uber, isn’t convinced bitcoin can be used as a mainstream form of payment.

Tesla announced earlier this week that it had made a $1.5 billion investment in bitcoin, a move that led to speculation as to whether more firms would follow suit.

Elon Musk’s electric car company said in a filing Monday that it would also start accepting payments in bitcoin in exchange for its products.

Meanwhile, Mastercard said Wednesday that it plans to offer support for some cryptocurrencies on its network this ear.

PayPal is hoping to allow its vast network of merchants to accept bitcoin and other cryptocurrencies as a means of payment, while projects like the so-called Lightning Network aim to speed up bitcoin transaction times.

Pieter Van Der Does, the CEO and co-founder of Adyen, told CNBC that volatility in bitcoin and other cryptocurrencies makes them less attractive for making transactions.

“It might not actually be helping cryptocurrencies if they are more like investment assets than a currency,” he said.