Failing to put money into a tax deferred account is a mistake in general.
However, I think you are the one that said you were making significant progress on killing credit card debt? That might be more than a legitimate excuse.
Let's see here...
I have contributed to my 403B ever since I started working for the university system in 2000. In 2006, I stopped contributing for several reasons... my financial situation had changed (no longer in school so not receiving that tuition tax credit and having to pay back student loans) and so I stopped contributing... leaving the money I had already put in, in. Over the last 2 years it has lost over 1/2 of its' value. During that time yes I could have invested in it, and all those investments would have been buying shares of funds while they were expensive and declining.. so every dollar of it would have been worth less now than when I put it in. I was "lucky" in that my financial situation at the time prevented me from contributing to funds that were about to tank along with the rest of the market. Instead I made headway into decreasing my personal debt which is way more beneficial in the short-term AND long-term.
Now... my situation has changed... I'm going back to school, freeing up some money every month to go towards investing in my 403b again and paying off credit card debt (still working on that but making significant progress... I only hope I can avoid most of the rate hike that the credit card companies are about to do to us average consumers) and now that I believe the economy is back on a slow upswing, I'm going to contribute again.
"it is always good to invest in real estate"... I can't believe how many times I heard that line before 2008. Thank god I didn't buy a condo/house *cough*Eric*cough* and stuck with owing more than my home is worth and with a monthly payment I cannot afford and unable to sell it.
So no... it is not ALWAYS a good idea to invest in a tax deferred company sponsored plan... USUALLY, yes... but it wasn't for me. I made the right choice and I'm benefiting from it now.
On the flip side... my co-worker JUST THIS MONTH stopped contributing to her 403b because "it has lost so much money over the past 2 years"... UMMMM... hello?!!!... now is not the time to stop!