It becomes a "war" when the poor start fighting back.
A single person making $10K (taxable income) in 2013 paid $1,058 in taxes... or ~10%.
A single person making $100K (taxable income) in 2013 paid $21,293 in taxes... or ~21%.
If 10 people each made $10K, they collectively made $100K and paid $10,580 in taxes... which is still less than half of what the one person who made $100K on their own paid.
[1] http://www.irs.gov/pub/irs-pdf/i1040tt.pdf
Edit: I did just get my taxes done so I might be a little more bitter about the topic than I usually am. But the numbers suck.
In the real world everyone pays the same $5 for a hamburger,
A single person making $10k has money left over to buy a little less than 5 hamburgers a day. A single person making $100k has enough money left over to buy a little more than 43 hamburgers a day. 10 people who make $10k can still only afford 50 hamburgers a day between them after tax, only a little bit more than the guy making $100k.
That's why we have a progressive tax system. We think the guys making $10k should be able to eat and the guy making $100k probably shouldn't eat 8 times as many hamburgers as the guy who makes $10k.
C'mon. I know you're aware that the rates for the tax brackets have changed over time. Surely you know that the top tax bracket was well over 50% for most of the 20th century, and is now lower than that.