I grew up in a middle-low income (but very intellectual) family in neighborhoods with good schools usually dominated by people with higher incomes. I'm thinking about how my friends and their siblings turned out, and ultimately, I think everyone turned out ok by their mid-late 20s. Some received some form of support longer than others but with a goal in mind, rather than "living in the basement unemployed playing video games". A few went through periods of greater materialism and snottiness in their tweens and teens, though. One friend in particular stands out, and if I had to guess, inferiority would play a role (she has a definitively angelic younger sister) but also her parents not holding her responsible for her behavior. She bragged to me in our teenage years about how she literally threw a fit until her parents gave her the 3rd bedroom as her own (previously used as an office), how she sneaked out to do whatever (make out with guys, go to parties), how the parents wanted her to go from her posh private school to public school since she wasn't putting in the effort to do well, but would get her a car if she chose that option. (Obviously, the correct answers here are: "Never give up, never surrender" and ground her for life; ground her for life, move her into YOUR bedroom for a while, and install a house alarm; and transfer to her public school *regardless* and make her take the bus or walk). She ended up, as I hear it, graduating the fancy school but then partying away her first year at college on the other side of the country and failing out, which I believe sparked a touch of tough love and marked the beginning of her turnaround into a decent human being.
If I were to list some major factors I think contribute to people growing up into sensible not-jerks, I think they would be:
1) Parents and their example. You're halfway there even caring how they turn out. But they'll also emulate and internalize a lot of your behavior (maybe without either of you realizing it). How often do you buy new things, or upgrade/replace your old things? How do you talk about "stuff"? How do you talk about other people? What are your first questions when they make a new friend? How do you respond to them and their actions, appearance, decisions? (e.g. if you ever say "You're going to wear that? What will people think?" you are reinforcing that what others think matters. If you stand in line for every new iPhone, your exhortations about the needlessness of having every new toy will fall on deaf ears.)
2) Responsibility. I've seen a lot of material recently about how helicopter or "steamroller" parenting ultimately results in helplessness, anxiety, and depression among college students. The more you do for your kid(s) that they can do for themselves, the more you are undermining their sense of independence and agency. The more you let them get away with (or worse, reinforce) negative behaviors the longer they will keep them. Teach them how to run a household by involving them (cook, clean, shop). Make them talk to their own teachers about poor performance before interfering; sometimes teachers are out of line; but that's not a first-resort assumption. Counsel them on how to solve problems rather than forcing whenever possible (I admit being banned from computer games for bad grades did me a lot of good at one point...but generally I could rely on my parents for good advice and not cramping my style). Finally, be open to well-reasoned, well-researched arguments; it's how adults justify their decisions and get what they want (instead of throwing a screaming fit). You want to reinforce that.
3) Deprivation (and lack thereof). I think short-term deprivation, like camping or retreating to a small primitive cabin, etc. can be really good for developing ruggedness, grit, and empathy. Things like having to carry water, use a nasty pit toilet, sleep on the hard ground, etc. Not to mention losing modern entertainment. I definitely don't think one needs every comfort and convenience and toy to have a good life. But, on the flip side, I think ongoing, long-term feelings of deprivation, even if they are artificially imposed or comparative (i.e. not having what friends have and they want, even if their needs in a strict sense are covered) can build up to cause resentment and/or splash out once they have some independence and start getting a paycheck. How often do we hear a story like "my spouse grew up very poor and spends every dollar they get their hands on" on this forum? I definitely think it's a fine line, but there's a distinction between raising a young shopaholic by catering to every whim, and being sensitive to the fact that kids are mean might exclude or bully a child who can't blend in sufficiently...maybe it's the wrong style or brand of pants, or they can't join in to go get sodas after practice, or they bring stinky weird food... there might be things that are incompatible with family values (video games, religion, etc?) but it's a "pick your battles" situation.
4) Generosity. Although we were on the lower end of the income spectrum relative to my peers, my friends were always welcome to come over to play, they would always be fed, they could join us for outings if there was room in the car (to the beach, museum, aquarium, hiking, etc). I don't think my parents ever asked to be paid back, and I expect sometimes they weren't. I think some of the jerkiest people are those who never learned to give freely, for the sake of giving and helping and the goodwill, without expecting equal monetary value back. So invite their friends over (even if the house is a mess), and your friends, too! Give to the food drive and the PTA. Watch your friends/family/neighbor's pets and kids as a favor. Maybe accept payment in homegrown lemons and then share a homebrew on the porch. Show them how to develop and value relationships (going back to #1) and thus *true* wealth and happiness.
Not an expert and not a parent, but that's my take on where good people come from. And while I wouldn't do a TV in each room, I don't think that alone is a death sentence for your goals.
