Bitcoin's long and tortured journey to new all-time highs this week has an unlikely hero in its story.

Why it matters: The SEC — whose leader Gary Gensler has been implacably antagonistic toward crypto — gave bitcoin an improbable yet undeniable seal of approval.

• The agency's (reluctant) green light has sent billions of dollars flowing into the newly minted ETFs, boosting its appeal among retail and institutional investors alike.

Driving the news: A number of developments — such as halving and true-believing "hodlers" who never lost faith — have emboldened the bitcoin rally, which has more than tripled in price since melting down to under $16,000 in the wake of FTX's late-2022 collapse.

• There had been clear momentum pushing it higher. Yet bitcoin's tear really picked up speed in January after the Securities and Exchange Commission approved exchange-traded funds after years of denials.

Follow the money: The success of spot bitcoin funds has led BlackRock to file paperwork of its own to get approval to park some of a bond fund into a bitcoin ETF.

• Prominent bitcoin investor Anthony Pompliano writes that is a sign of "a potential new source of capital into bitcoin — trillions of dollars of existing funds that need to find a home in an asset that performs better than the current asset allocation."
• A groundswell of big Wall Street banks are also contemplating their own moves into the space.
• "When the ETFs got approved by the SEC, people said 'game on'," CK Zheng, the founder of Palm Beach Gardens-based ZX Squared Capital, tells Axios. He added that it wasn't just retail players but big institutions that buy and "stay put."

State of play: After a cryptocurrency "winter" that lasted two years, the digital token set a fresh record above $69,000 on Tuesday.

• In true Bitcoin fashion, it rapidly gave back 10% before recouping some of its losses on Wednesday.

What's next: The daily emission of new bitcoin will drop in half sometime in April (as it does every four years), which is likely to boost the spot price. A wave of excitement has kicked in a bit later after each of the last three.

The bottom line: The darkest days of crypto's winter appear to be behind it, with the sector's worst offenders — looking at you, Sam Bankman-Fried — either jailed or facing justice.

Editor's note: This story has been updated to correct the first name of bitcoin investor Anthony Pompliano.