Several game blogs I follow have talked about how they seem to have too many Steam games. They buy a ton of games on big Steam sales but never end up playing them. The usual story is that they have a library of one hundred Steam games but only play about five new games a year... and they are still buying twenty five new games a year because they look cool and for five bucks how can you go wrong?
My Steam library has seven games in it and all have dozens to hundreds of hours. Sales, they don't so much work on me.
Tobold thinks this is a widespread phenomenon and that this is going to lead to some kind of massive game industry crash as people notice that they are paying for games they don't use. Eventually people will catch on and just stop buying games at all until they have played through all of the games they have. If we assume everyone is a perfectly logical actor and that money is extremely tight then this makes sense, but neither of those things is true.
Just look at the garment industry. That new sweater that you bought even though you already have six sweaters? A total waste, but what a bargain at half off! It would be a waste of money *not* to buy it! 50% off sales still generate massive amounts of buying even though people have had awhile to try to learn that 50% isn't really 50%. Like ten or twenty thousand years, at least. I am pretty sure it took about fifteen minutes after the first person traded berries for a hunk of meat for someone to figure out that offering meat for ten berries then dropping the price to five berries would get people interested. Fact is, we know that people continue to accumulate far beyond their needs, even far beyond their ability to use the thing they are buying at all.
There is every reason to think that this will apply to games in the same way. People are going to continue to buy new shiny things at big discounts and then not have time to play them. The people that are clever enough not to do that already aren't doing that, and last I heard Steam was making a bajillion dollars. All those people supplying the bajillion dollars are going to keep on doing that.
You can't go too far wrong assuming everyone is going to buy crap they don't need, and Steam is assuming that in a big way. The smart money is on that working well into the future.