The only pay cash crowd is speaking to those who have trouble exercising good judgement and control. No different than AA mantra of never taking a sip of alcohol or Gambler's Anonymous decreeing one should never make a bet. Most of us can have a glass of wine or take a trip to a casino and not spiral into the gutter. Same with credit, use it wisely and you can make your life better. There are even flaws in the old saw about always living below your means. When you wake up someday and find yourself physically unable to fullfill a dream will you be comforted by the fact you could have done it, it was within your means, but you didn't because you "lived below you means"? Often we regret what we could have done more than what we have done. Credit is a tool. Used wisely it can build great things, used poorly it causes damage.
