About 2.5 years ago Juan Guaidó was about to assume the presidency of Venezuela, despite never even running for the office.
However, Guaido missed his moment, because, well, he's a fraud and a crook.

(Reuters) - Venezuela’s state prosecutor’s office said on Friday it would open an investigation into Juan Guaido after the interior minister presented photos on state television showing the opposition leader in the company of two suspected members of a Colombian drug-trafficking group.

And this wasn't his only scandal of that year.

(Reuters) - Venezuelan opposition leader Juan Guaido’s faltering efforts to oust President Nicolas Maduro are facing a new challenge in the form of an influence-peddling scandal that has left disillusioned Venezuelans wondering if Guaido’s moment has passed.

By March of 2020, the United States was proposing a transitional government that would exclude both Maduro and Guaidó from the presidency. So you would think that his window of opportunity had closed more than a year ago, right? The EU stopped recognizing Guaido as president nearly a year ago. According to polls in Venezuela from early 2020, only 3.0% recognized Guaidó as president, while 88.3% of respondents believed that Guaidó was incapable of governing Venezuela.
His pathetic coup attempt in May 2020, didn't help his cause. Even his own political party in Venezuela wants to ditch him.

“There is an attempt to continue extending the Guaido government, but that does not help the Venezuelan people, and I’m not going to support it,” said Henrique Capriles, a former presidential candidate from the Justice First party whose support for Guaido, which was key in 2019, has cooled as the interim government has stumbled recently...
The dissent stems from the Guaido government’s failure to oust President Nicolas Maduro and discrepancies over handling of assets abroad, the people said.

Most importantly, Guaidó stopped being an elected member of Parliament in January 2021. He doesn't hold ANY office now. So why are we still talking about him?

There's two reasons why Guaidó is still relevant. 1) Because Washington still backs him, and it has no Plan B, and 2) those "assets abroad" and their "handling".
Did I mention that Guaidó is a fraud and a crook?

Opposition politician Juan Guaido would have stolen US$40 million of Venezuela's foreign assets that were aimed at humanitarian aid, according to a report published by The Washington Post.
The U.S.-backed opposition needed money to implement its plan to overthrow President Nicolas Maduro's government from abroad.

According to The Washington Post, Miami-based Venezuelan businessmen Jorge Reyes and Pedro Antar offered a plan to get that money by seeking Venezuelan assets in Latin America.

The assets included companies' shares, cars, houses, and other properties owned by the Oil Company of Venezuela (PDVSA).
The U.S.-based outlet had access to reports on contracts signed by the Guaido's delegates during the process of identifying and recovering the assets.

"Troconis signed with a South Florida law firm to recover a U.K.-based account that contained nearly US$1.7 billion owned by Venezuela's Food Ministry," the Washington Post revealed.

Another contract disclosed that Guaido condoned half of the US$269 million debt that Paraguay agrees to owe PDVSA. Although both agreements were made under Guaido's consent, he denies any involvement in this scandal.

As you can see, these are extremely large amounts of money.
However, Guaido is about to gain control (aka steal) of the largest chunk of wealth yet.

The UK Supreme Court has prevented Venezuelan President Nicolás Maduro from accessing $1.95bn (£1.4bn) of gold stored in the Bank of England (BoE).
Mr Maduro says the cash will be used to fight Covid-19 in the country.

The Supreme Court overturned a prior Court of Appeal ruling, meaning only opposition leader Juan Guaidó, who the UK considers as the legitimate leader, can decide what happens to the gold.