Maybe because you're white-washed perhaps? Guys don't really look at hair color when choosing a girl. Perhaps black guys do like it but aren't attracted to other parts of you. You could just live in a white neighborhood and there's not a lot of black guys to begin with.
You don't have to date white men. You can find the right guy for you.
You have an alternative (punkish/scene type) look that most black guys don't go for.
What type of black guy do you want?
If you wanna increase your chances of attracting black guys you might wanna change your style. But if that is a part of you then don't change for someone else...IDK but most black guys prefer long straight hair without all the colors. Unless they go for the hoodrat look but I don't see too many black guys liking the alternative look