In the grand scheme of things, it's a pretty small waste. I'm sure that every person who has replied to this thread has wasted money/environmental resources on some item for their bike that is less useful than a new tube. The act of riding a bike to work instead of driving pretty much negates any possible wastefulness derived from not patching an old tube. For those that choose to get new tires rather than replace, there could be lots of plausible reasons. It's quite possible to have lots of sense & still decide that a new tube is worth it.