Well we disagree in many ways.
1. Your slogan; "life isn't fair" is meaningless. It can be used to justify anything including (as you suggested) sawing off someone's legs so you can win a race. Let's be blunt.
2. My preference would be that my children have advantages over other people's children. Of course, if other people's children had advantages over my children, I would be upset. Having a level playing field seems like the right way to resolve this problem. The question is what this means.
3. I happen to be White and male with a good job. I have political power, and can impact policy; particularly in my local community. If a teacher yells at my kids in way I don't feel is justified, there are ways that I can rectify the situation. My sense of right and wrong makes me feel like I should look out for other kids, even if their parents don't have the standing or power that I have. If something doesn't strike me as "right", I speak up about it. Whether this is "fair" or not doesn't matter (as I pointed out above).
3. Life will never be perfect, but there are ways to make it better. We can talk about what this means. But this is my country, and I have a voice. Again, if you don't think this is fair... it still doesn't matter.
4. I hate ideological bubbles. Most Americans are either conservatives who hate liberal ideas, or liberals who hate conservative ideas. Every marches in lock step without thinking for themselves.
When you attack "the liberal left" and "Marxists" in a general sense without any rational discussion of individual idease, you show a lack of critical thought.
Intellectual independence, the ability to objectively judge an idea without regard to political ideology is a good thing, and sadly most people sit at the extreme and spend their time lobbing these mindless attacks at each other without ever listening, considering or thinking.
I call out what I see as bullshit from both sides. And I will accept ideas that make sense from either.