Mr Green's Sevco consortium is unlikely to cash in its chips to former Rangers manager Walter Smith or any other would-be purchaser in the short-term unless it at least doubles its money, they believe.
They say Walter Smith's offer would leave the consortium with a profit of just £500,000, which would not be good enough.
Mr Green completed his purchase of the 140-year-old club's assets with £5.5 million, which is believed to be in the form of a loan that the club repays, having paid just £2 for Craig Whyte's shares.
Smith, the former Rangers manager, launched a last-minute bid of around £6m with businessmen, including Douglas Park and Jim McColl, and urged Mr Green to step aside.
Donald McNaught, business recovery and insolvency director at Johnston Carmichael, said that Sevco would be unlikely to sell unless it doubled its money.
"[Mr Green] has said he is in it for the longer term," he said. "And the balance sheet talks about £100m-worth of assets potentially acquired debt-free for less than £6m, which, on the face of it, is a fantastic deal.
"If you look at Rangers' footprint in terms of season ticket sales, merchandising and other revenue streams, the potential is there to make an excellent return on £5m."
Neil Patey, an Edinburgh-based finance expert who helped broker the deal that put Chelsea in the hands of Roman Abramovich in 2003, agreed Green's consortium was sitting on a potential goldmine and stood to make tens of millions.
"Celtic's market valuation right now fluctuates between over £30m and over £40m," he said. "Rangers are worth a whole lot more debt-free than it is currently.
"Rangers would be worth tens of millions debt-free. [Mr Green] could at least treble his money [in the longer term]."
He added: "Charles Green is doing what Craig Whyte tried to do. Craig Whyte just got it wrong. He got the public vote card wrong."
Mr Patey, football financial expert at accounting giant Ernst & Young, said Walter Smith's consortium might tempt the group to cash in if it offered £11m – double the price paid – but that £500,000 profit was simply no enticement.
But he agreed there remained "uncertainties and risks" to getting a newco Rangers stable. "[Mr Green] would think they won't get to the point where they will be permanently expelled and that at some point Rangers will get back to its former glory and be established in the SPL and worth a lot more money.
"You can see fans getting behind Walter Smith hugely and if fans do not buy season tickets now there would be questions in the public arena over how much further money Charles Green has," Mr Patey said.
"He still has to fund working capital next season and if he doesn't have that money, that makes things financially very difficult for him.
"On top of that, some of the players can refuse to join his newco. And if the players say they don't want to join the club, the value of what he has got in the short-term erodes."
He said Sevco also has to worry that the investigation into Rangers' previous use of dual player contracts could end up "sticking" to the newco. This involved using Employee Benefit Trusts (EBTs) to pay dozens of players over the last decade.
If it is proven the club used EBTs against league rules, Rangers could be stripped of titles.
"You could argue legally that it doesn't affect the newco but in the sporting context the authorities will say it does," said Mr Patey. "They'll say if you want to be Rangers, join the SPL and retain your history, you have to take the bad stuff as well."