Bail was denied to the "very serious flight risk" on Wednesday and the 27-year-old remains behind bars on an expired visa accused of dealing with millions in criminal proceeds.
Tang was arrested in November along with his co-accused Han Xiao, 25, awaiting flights to Hong Kong a month after two younger men were arrested at their inner-Sydney apartment.
The four, all Chinese nationals, are accused of involvement in a sophisticated investment scam involving social engineering, dating and employment sites, and messaging platforms to gain the trust of victims who were directed to fraudulent and legitimate foreign exchange and cryptocurrency investment platforms, Australian Federal Police said when announcing the arrests.
Opposing an application for Tang's release, crown prosecutor Edward McGinness alleged in court on Wednesday Tang recruited, controlled and directed people lower in the scheme's pecking order, including his co-accused.
There were also dozens of other people who had not been arrested but appeared involved in the scheme, including some who might have directed Tang, and purchased the ticket to Hong Kong he was arrested with.
Tang should remain behind bars due to the previous attempt to leave the country, his lack of ties to Australia, a strong case supported by "voluminous WeChat messages" the AFP are still translating and the seriousness of his alleged offending, Mr McGinness said.
The court should hold grave concerns he would attempt to flee.
"There are vast sums of money which might be available to Mr Tang and many people who might provide it," Mr McGinness said.
Tang's lawyer John Kahn said Tang planned on coming back despite having a one-way ticket and would not have waited more than a month after his co-accused were arrested if he wanted to flee the country.
His alleged access to significant funds was also questioned given Tang had been accused of dealing with proceeds, as an intermediary directing money from the United States to China.
"That's what happened in Australia, funds come in and funds go out," Mr Kahn said.
Indictments allege Tang and Xiao dealt with more than $10 million and were reckless to it being the proceeds of crime.
Mr Kahn said discussions between the two co-accused suggested Tang was following orders rather than giving them.
"They are discussing that there's nothing illegal about what they're doing, and the worst that can happen is the account being closed," Mr Kahn said.
Tang may have been naive or stupid, but has no prior criminal record and has been in custody for six months already, with more delays expected in the prosecution.
He has been in Australia since 2015, moving as a teenager, however his mother has come to Australia since his arrest.
She offered to put up $200,000 as surety, well short of the $1 million sought, and have Tang live with her in Kempsey.
His student visa expired in February, Mr Kahn said, meaning Tang could be detained upon release anyway.
Magistrate Miranda Moody said she would "most certainly" refuse bail as Tang was a "very serious flight risk".
"There's a lot of money involved here, this is a sophisticated criminal syndicate and his place … may be a significant one in the scheme of things," Ms Moody said.
Tang and his co-accused Xiao, as well as Weizhe Huang, 19, and Jiachen Jiang, 20, return to court on July 19.
