Timon enjoyed having more money than all his friends, and wanted to be kind to them by giving gifts. But were his friends really his friends, or merely hanging around because he was richer than they and bestowing him with praise because he gave them things? Their responses to Timon's request for loans in the next act show that they aren't willing to help him out when he is in a bad spot, which is a strong case for them not being Timon's friends. And they are far less generous than Timon ever was, since he was always glad to loan money to help get a friend out of jail, etc.
Yet his friends and acquaintances loaned Timon money before the action of the play, and their calling their debts due causes this crisis. Perhaps before they hung around Timon's house because they couldn't believe the extent of his generosity, and they wanted to be around to witness its success or failure. And perhaps they then lent him money because they actually wanted to help bring about his downfall. Whatever the speculation, the facts remain that his "friends" would lend money to Timon when he seemed to be rich and likely to give them gifts, as well as pay back the loan, but when he is in trouble, none will help him. His friends behave more like an impersonal bank than as people who have previously benefited from Timon's generosity and might owe him some kindness.
This scene contains an exchange between the servants from the men who Timon borrowed money from, who seem to be sent by Timon's friends but also say they are in the employ of usurers. This detail may be mistakenly unclear as the result of an absence of revision, since this play was not performed in Shakespeare's time. The exchange seems fairly extraneous to the action, but is merely a change to get a Fool onstage, to make bawdy, fast-paced jokes with the servants. This Fool, who doesn't appear again in the play, probably references all the other fools in Shakespeare's plays, who were always distinguished by their ability to be wiser than wise men, and far less foolish than many of the main characters. In this case, Timon may have been the biggest fool, for his inattention to his purse and his belief that his generosity would be one day repaid.