Nobody is arguing to make things harder or worse for those with privilege. Generally people are asking for equal consideration and opportunity and a recognition of past and existing injustice.
One argument against this is based on the philosophical concept of a Veil of Ignorance[1]. We should create the rules of society as if we don't already know what our position in society will be. No one wants to live in a society where they could be randomly selected for organ harvesting, for example.
As a result, it sounds like you're saying "screw you, I got mine". We can flip the question around: why does this majority deserve better opportunities? There aren't very good answers to that question.
The main thing I'd point out is that unlike your metaphor society is not a zero-sum game.
No, if you make things worse for 90% of the population, and make it better for 10% of the population, the total is worse and therefore the average (mean) is worse.
Edit: an example. Let's say the first 9 people rate society at 10 points, and the last one rates it a 4. Total 94, mean 9.4, median 10. Now change things around so everyone is equal and ranks things a 9. Total 90, mean 9.0, median 9. Even though the majority is almost as happy as before, and the minority is much happier, most measures come out worse.
We're assuming in this totally contrived example that points are a measure of total resources + opportunity in our closed system, since we're implying a redistribution of a fixed pool of resources^1.
So, the total in the "after" picture would still be 94 and thus the mean would remain at 9.4 and the median would be 9.4 - (and down from 10).
I'm not a fan of arguing from averages - realistically, the picture is more like 1 - 1000pts, 2 - 100pts, 3-50pts, 4-30pts, 5, 6-7 - 20pts, 8-10 10pts
~ 1270 total, avg 127, median 20.
But these are all contrived examples (in the above I'm more leaning on income distribution, which I've reproduced from memory and may be skewed). If we equalize the above, the median would go up.
The argument for redistribution can be made on an economic/statistical basis - but the argument for equality, I think, is ultimately moral. It's not about fairness per se, but about justice.
^1 Not quite my stance but for the sake of argument.
That's a massive leap in logic. Society isn't a simple one in, one out metric.
That is an argument no one is making. What are you talking about?
