29 isnโt too old to KEEP grinding as a rapper, hoping to gain some momentum and an organic fanbase. You may not become Drake, but you can become a Devin The Dude type rapper with enough content and a good understanding of your demographic.
But 29 is definitely too old to START from scratch as a rapper, with zero industry connections and no skills at beat making. Nobody is gonna put money behind and bet on an unknown 29 year old