There’s an idiom or figure of speech that is OK to use in spoken conversation but makes you look dumb if you write it. It goes like this: that (adjective) of a (noun) or too (adjective) of a (noun) or how (adjective) of a (noun). Examples:
• I wouldn’t need to be that rich of a man.
• Paul McCartney’s grandson isn’t too rich of a baby, is he?
• I don’t care how rich of a star Ellen is, she’s no Oprah.
The problem is the word of. You don’t need it – each example means the same thing without it – and in written form it carries the whiff of the backward, ignorant writer. If you speak this idiom out loud nobody will raise an eyebrow, but if you write it on a page or screen someone may scrunch up a nose.
Back away from the of.