I was just browsing through my games in the Steam client, and realised I have a huge list of excellent games waiting for me to play/replay (then I have another list of games on GoG, Origin, and Humble).
Then I asked myself how I can justify buying more games, even if they cost a penny in the Steam sale?
I also found it stressful to look at the Steam page looking for something new or interesting to buy, and later trying to find a time to play the excellent games that I already have.
To summarise, I just can't justify buying more games on Steam with my huge backlog, cheap or not.