Running gives you better health, so if you value your health then running, even on treadmill, already gives you something of values.
It makes no sense to compare debate to radically different activities (like programming or starting a startup). I'm not arguing that debate was the best thing that anyone can do, rather that it's a worthwhile and not totally bullshit activity. I understand if you don't want to do it (different strokes for different folks) but I gained a lot from it and I think it deserves a certain amount of respect. I would never disparage a tennis player for having wasted his time just because I find it tedious running back and forth. I would respect him and want to learn about tennis from him.