The Communication Deterioration - S8-E21
Penny: You are a wise man.
Sheldon: Well, Penny, who's smarter, the wise man or the person who comes to him for advice?
Penny: Oh, I guess you're right. Maybe it is the person who asks.
Sheldon: No. It's the wise man. That's why he's called the wise man. You know how I know that? I'm the wise man.





Suggested correction: Not being able to afford doesn't necessarily mean he doesn't have the money, especially a man like Sheldon. He works with a budget and he sticks to it. In his budget he has a certain amount set aside for rent, anything more than that and he can't afford it alone.
Nonsense. If he was sticking to a "rigid budget" he wouldn't have even thought of lending a hopeless credit risk like Penny a single cent. Instead he throws a huge bankroll at her without even discussing a repayment plan.
Rubbish, I stick to a strict budget but still have the money to lend to close friends. Like Penny is to him.
He might have different budgets for different things. People could get a higher margin because they could be of more use to the scientific mind of Sheldon.