Are gens worth it? Purely subjective, and depends on the person asking/answering the question
Based on the sales of Rolex watches though authorized channels (new) and secondary vintage and preowned, there are many people out there who believe they are. And, they'd be right.
However, there is something to be said about reps. While they may not carry the monetary value intrinsically, they are still loads of fun. I have more fun building my own watches than simply buying...