Well, I don't think we can just definitively say "No" without knowing details of your case. After all, according to
http://www.uscis.gov/graphics/publicaffairs/factsheets/affaqa.htm,
"Which immigrants must have sponsors?" - "... In addition, employment-based immigrants who are coming to work for relatives or for companies where relatives of the immigrant own 5 percent or more of the company must have sponsors." We don't know that it's not your case.
Generally speaking, either an employment letter or an affidavit of support is needed to prove that you won't become a public charge. In EB-1 EA cases though it's a little unclear exactly what is needed, as you don't
have to be employed... And I-864 doesn't always apply. Your
latest tax return could be useful, if it shows enough income. Or there is another affidavit of support,
I-134, where a sponsor doesn't have to be a relative, but I haven't found any regulations on when that has to be filed. USCIS can always request it if they need it. So when I was filing I-485, to be safe, I included the following sentence in my cover letter,
"At this time I am not including Form I-134, Affidavit of Support, as per legal advice I received, but I’ll gladly provide it should you require it."
I hope any of this helps!