I used to believe that kids from well heeled families would all grow up to be elites because from an early age they enjoy all kinds of high quality resources. After I became a teacher, I realized myself to be wrong. Some of those kids do indeed make full use of their advantages and advance into the elite. However, many stumble into sloth because from birth their needs are all met, as if by apples falling from a tree. Having no idea what “hard work” might be, they later find their lives to be bleakly empty. This has led me to revise my previous belief. Perhaps wealth, in removing the need to stand on one's own, can also be a curse. I moved "from an early age" to a position where it would more clearly modify "they enjoy". I moved "indeed" closer to the verb because that is what it modifies. I say "what hard work might be" rather than "what hard work is" because you are talking about an imagined abstraction, an idea that the children could not even imagine. The modal verbs are ideal for this purpose, especially the past tense ones: might, should, could, would.

I used to believe that *kids /children from well-heeled families would all grow to be an elite /privileged because they enjoy all kinds of high-quality resources from an early age. After I became a teacher, I realized that I couldn’t have been more wrong. Some of them /those kids make full use of their advantages and indeed grow to be an elite [indeed]. However, many of them are incredibly inane and ignorant because they already have everything they need from birth. They have no idea what “hard work” is, and their life is pathetically empty. This makes me reflect on my previous thoughts. Maybe sometimes wealth can be a curse that prevents *kids/ young people from standing on their own (two) feet.