It seems to me that most sales offices exaggerate the amount of units already sold, kind of industry standard.
I don't think the intent was to steal, the developer seemed to have genuinely wanted the project to move forward. Unfortunately his incompetence was too much to overcome and he kept digging a financial hole he couldn't get out of. He just borrowed to fix a problem and then kept borrowing to fix ongoing problems. Soon it was too much.
What I don't understand is how did he have access to the deposit money if he had yet to secure financing with the bank??? Aren't eh deposits held in trust with a notary until the bank officializes financing approval? Who approved for those funds to be released, the notary??? If thats the case then the buyers have a real case against him and he will be royally screwed in court