Bitcoin extended its eye-popping rally, approaching $19,000 for the first time in almost three years, while enthusiasts predict it will quickly surpass its all-time high.

The largest cryptocurrency gained as much as $875, or 4.9%, to $18,821 on Friday. Bitcoin has jumped more than 15% this week. Having more than doubled this year, the surge is spurring memories of its 1,375% rally in 2017 that took it close to $20,000. It plunged 70% the following year.

“There is little to suggest this rally has run out of steam and all signs point to a run at the all-time high in the near future,” said Denis Vinokourov, head of research at Bequant in London.

Crypto fans cite wider institutional acceptance after PayPal Holding Inc.’s October decision to allow customers to access cryptocurrencies led Bitcoin to spike above $13,000 for the first time in over a year.

“When we think about who we see getting involved in the space and seeing how many more access points are being opened, that can further expand the base of investors participating in this asset class,” said Michael Sonnenshein, managing director at Grayscale Investments, which offers the largest Bitcoin exchange-traded product. “We’re very, very encouraged by the prospects for this space overall.”