How do we develop empathy in kids?

I like to mimic the situation to my nephew. Like for example we we're walking at the mrt then there was a handicapped beggar asking for money. The beggar had no hands. Like it was a stump from the elbow down. So i gave the guy some money. Ok so straight up no diss, but my nephew, who is 8, then commented "eh uncle, how come you give the stranger money but you never upsize my meal?" he didn't mean it in a malicious or like i'm better than thou kinda way. He was generally curious about why I chose to give money to a complete stranger vs my own blood. Of course to preface this, me and his parents have been telling him to save up for a rainy day bla bla bla reward yourself end of the year after exams bla bla bla, cultivate that habit sorta thing. So I told him, "eh Ahmad(not his real name because he is just a child) got other people who don't even get allowance how to save like you. Some people, the allowance come from strangers. You're lucky, your mother and me give you money to eat and enjoy" Then this boy also one kind, he complained about him having to study hard and pass exams with A+ or something, go for cca, eat vegetables, just so he can get extra allowance to buy ice-cream after school. Like wah lao the guy no hands he can't even eat ice-cream. So when we got home i tied his hands up. Like you try and touch your shoulder on your respective arms, so your arm folds, then I tied that part. so like exactly like the beggar. Then i told him okay now i put $50 infront of you on the table. If you can take the $50 note and put it in your pocket I let you keep it, can upsize your meal long long. He tried. He genuinely tried. After he exhausted himself, he could barely kiap the note with his elbows, let along put it in his pocket. I took the $50 and just shoved it in his pocket for him. and of course I untied him after that lah. He said it's damn hard to pick up the money, like he was sweating and all. Then BAM, I told him ah. You think that beggar can open a book to read? Can eat ice-cream? Can double dip nuggets in curry sauce and chili(coz my nephew likes to do that)? Even I give him money, he cannot spend, need someone else to help him buy food. You must always help people who cannot help themselves. Then this boy started crying and saying sorry to the beggar,(who wasn't even there. We were at home lol). I think he learnt his lesson. But It's a bit of tough parenting style la. Not every parent wants to do it this way. And confirm chop his parent's wouldn't either. Im his uncle so maybe a bit of leeway hahaha. But I know for sure now he'll think twice about other people and not himself. At least for a while. And that helps me sleep at night. That my nephew is trying to be a better person. If we don't teach the younger generation how to be empathetic, who the hell is gonna look after us when we're old and frail right.