It takes a couple of years but most people eventually realise that they should stop buying games cos they're cheap and play the ones they already have ><
*in most circumstances
It has kind of happened for me. I've only bought Just Cause 2 in the sale so far (even though i've been tempted by Magicka and SMB). I probably won't bother with any others tbh. Other than those, the last game i bought was The Witcher 2 and before that Crysis 2 i think.
Though that is only really because i started playing all the games i bought in the last Steam sale

Recently played Metro 2033 (£3 in steam sale) FEAR and FEAR 2 (both in steam sales) and Civ 4 (£4 in steam sale). The way things are going i don't think i will be buying many more games for a while. Only Skyrim and Deus Ex