Was he fifty at birth?
His first album was 2003; 'Get Rich or Die Tryin'. If 50 cents was his valuation then, that would mean Curtis Jackson's valuation was 22¢ at birth in 1975. Assuming he follows a somewhat arbitrary inflation rate of 3%. (This is also assuming he is not an asset of higher expected return like property, stocks, or bonds.) Putting him at a less attractive 99¢ today.
If he is the the currency himself, rather than being valuated at 50¢, then he would have devalued. This would put his value at around 27¢ today and $1.68 at birth.