It's not as if Steam games are universally cheaper all the time, across the board. But if you only ever buy when there's a sale on, who cares? Since that's the only time I ever buy, the price of the game when I'm not buying it is kind of irrelevant to me.
Honestly, I don't know why that is -- why console games cost more for the same game than the PC version. I'd expect that distinction to disappear over time. No idea why it's still around, actually.
Trade ins may still work, but it's not universally cheaper to do trade-ins than digital. And you don't have to deal with the post not delivering it one day, or them showing up when you aren't there to answer the door and now you have to go to the depot just to get your physical copy. And you don't have to worry about whether someone's gonna send you a bogus disc or whathaveyou from Ebay. Granted, that's less of a concern these days, but you could still get ripped off.
Personally, I find buying games digitally to be cheaper and more convenient than buying games physically -- most of the time. There are some cases where that's not true, but that doesn't really bother me one way or the other. If you like the physical copy, that's cool. enjoy it. I'm not trying to take that away from you (although the gaming companies will, eventually). All I'm saying is that the digital version really isn't as bad as people paint it to be. There might be advantages, depending on one's perspective, to one version or the other, but digital is not the end of the world the way some (not you) have painted it.
