I haven't been in the hobby long enough to know how it would be after several years of turning over a collection, but after about 3 years I've looked at it as a hobby where anything I do to a game, including shopping it and improving it, is part of the fun I get to have with it. In some ways I hardly look at them as retaining any kind of value, and that aspect just comes into play as an added bonus if I need/want to sell or trade.
Sure, breaking even or making money when selling would be great, but if it's all about return on my investment, I don't think it would be as fun.
I'll take a "loss" to get something else I want. For example, I've traded 2 games for 1 before. I know the value I traded was a little greater than what I was getting, but it was a game I wanted far more than the 2 combined and the trade was convenient, so I did it.
I guess it would all come down to whether or not you're ok leaving a game in unrestored condition while it's in your possession. I know I have games in various conditions with the thought that I'll eventually get around to restoring them, but I play them in the meantime and they're still potential trade or sale fodder if something else comes up.
At the end of the day, probably the best policy is to make sure you're having fun. It's a hobby, after all.
