It doesn't seem beyond at least exploring as a thought, if something can be done with the urine, though perhaps something more refined than drinking it. Perhaps a chemical separation to reclaim the amphetamines, because most of them pass through you unmetabolized and completely unchanged, still the exact same active drug. If you used a gram, you will excrete 2/3 of a gram. I wouldn't really think twice about someone deciding to experiment with drinking it. Couples engage in sex play quite commonly with urine, including consuming it. It's a bit weird but not batshit.
That said, I still think it is excreted over time. I can't see drinking glass after glass and it would get hard on one's tummy. but if there was a relatively simple way to exctract it. . .apparently there is a huge industry of selling a kind of steroid compound that pregnant women excrete in their urine, at the rate of about $15 000/day worth.