I didn't understand the logic of the first scenes of Requiem for a Dream. If Harry needs money, why not force his timid mother into giving it to him? Why drag her TV across a mile and pawn it? Why doesn't his mother give him the money when she sees him dragging away her TV so she doesn't have to go through the usual rigmarole? After all, she has money which she gives to the owner of the pawn shop.
Because most likely she doesn't have the money (at that moment)
Sara and Harry are quite poor - I don't remember if her source of income is mentioned, but it is definitely a meager one - she is a widow, so maybe a partial pension from her husband? Some sort of benefit? In any case, it wouldn't be much, and quite probably partially paid in food stamps, which you can't exchange for drugs.
In other words, she doesn't have any cash on-hand that Harry could take, so he is forced to pawn the TV for it. Sara is able to get it back when she manages to get some money.
She has the money, he said it himself in 20 mins you will have it back...
It's because she doesn't really love him and why he's a user.
In the beginning, you see a photo of them. He looks skinny and is uncomfortably holding the same arm he later loses. Foreshadowing what is to come. She cared more for the red dress and appearance then and now. He never shoots up in the same arm she was holding in the pic. Probably the only time she showed any affection.
She was too embarrassed to sit out front with her lady friends due to Harry's visits to take the TV. She wanted everyone to see him as a bad guy.
He later comes back and she's out front only due to being invited to some show.
He tells her about the new TV and she didn't care. How nice would it been to show her friends her son got her a new TV...
When he leaves he cries and shoots up in the cab...
She's hospitalized in a fantasy of publicly saying she loves him in which he's looking healthy and clean...
If he OD she probably wouldn't have been hospitalized and there would be no need to longer talk up Harry but grief him.