It's been a long time since I was a child trying to run a business, but gift cards as a payment proxy worked well back then.

I'm curious, how do you sell those gift cards after receiving them as payment? Are there legitimate businesses that don't just give you cents on the dollar? Or is this something that only works on a small scale until your private needs to order on Amazon, Netflix, etc. are met?

Not selling. As a 15 year old I had no access to a debit card or credit card. In order to buy computer equipment, pay hosting fees and pretend to be a 19 year old computer programming student, I needed to buy visa gift cards and use them for regular purchases. It wasn't until I was doing it for two years that I was allowed a debit card.