Absolutely.....for some it's been really good.
I must admit that I cleared out a lot of my own 4 L .com domains a couple of months ago. I believe that the overall trend for this category of domains will trend down as the underpinning value supported by businesses just isn't there. The vast majority of domains are purchased with the hope that the purchaser can resell them for a higher number.....there's a limit to this business model.
What concerns me is the status of the Chinese economy and when debt will force a slowdown that will have worldwide ramifications. Likewise, I really wonder whether the US is out of trouble or whether the real state of affairs is hidden. Time will only tell.