Mr Vlahos, 44, on Friday told a Sydney court he "regularly" checked a joint Westpac account that he opened six years ago with friend and colleague Daniel Maxwell, who now resides in Dubai.
He said the account, which he accessed online, was used as a hub for funds earned through his punting club.
Mr Vlahos told the NSW Supreme Court he had checked the account on Wednesday and could not see any problems with it, before being told the account - which had more than $194 million in it - no longer existed.
"I was shocked and devastated, and I didn't believe it at first, because I've been accessing it from my laptop," he said.
"I'm worried about everyone's funds in the account, including mine, which was a substantial amount. Shocked is an understatement. I'm very upset."
The court was told the account could only be accessed with an ID number and an automated eight-digit code from both Mr Vlahos and Mr Maxwell, that changed upon each login.
It is understood some of the members of the club had more than $1 million invested in the scheme, which claimed to provide returns of more than 25 per cent a year.
There could be several hundred members of the club - including senior people from the AFL, the media, the building industry and retail worlds.
The main 20 members drafted in others, who in turn brought in more members.
Outside the court, Mr Vlahos said he had invested heavily in the punting club and BC3 Thoroughbreds and was yet to pay off a mortgage for a Torquay property.
The revelation of missing funds came after Mr Vlahos, who bought Black Caviar's half-brother and a stake in a horse linked to the Mokbels, told members of his club he was closing the doors following their concern over payment delays.
Mr Vlahos told the Herald Sun last week the members would be paid within two weeks.
But on Friday he told the court he had "no idea" where the money could be.
"I haven't contacted Westpac yet to confirm whether this is true," he said.
"I spoke to (Mr Maxwell) yesterday. I was pretty emotional and angry and asked him to prove the account existed.
"He said he would talk to his contact at the bank and that it did exist, and now I haven't heard from him since.
"I think the next step is going to the police to ascertain what's going on, as well as dealing with Westpac."
It is understood the court case was brought by disgruntled punters club members.
Mr Vlahos will return to court next week.