Because Caucasians get the other 10 months out of the year to celebrate their heritage? And are more than welcome to celebrate their heritage during the other two months too?
Justin Wilson, the famed Cajun comic, once told a story about two duck hunters who pounded on the door of the local game warden, demanding "We want one more month to hunt duck!" The warden, clad only in his union suit after getting out of bed to answer the men's hammering on his door, said "What?" Both hunters repeated, "We want one more month to hunt duck! Duck season ends tomorrow, and we want one more month to hunt duck!" The game warden looked at both of them, asking "What you gonna name it?" The hunters looked, mystified, at the warden. "What you mean, 'What we gonna name it?'" The warden replied, "You already hunt 'em 12 months outta de year - if you want a new month, you gotta have a new name for dat month."
Americans have 12 months a year to be proud.