Waxing

Of course, one reason the rock stars can speak of their basement-and-dog-food so fondly is because it enventurely came to an end;it didn't last forever. And with all the world tours and parties, this era of creating their seminal work soon became a distance memory. So quite naturally, they miss it. But there were still "eating dog food" after a few decades, I doubt if they'd be waxing so lyrically.

Could you tell me what it means here?