The (eventual) savings is incidental.
It's about improving the quality of your life, and not being a sucker for marketing hype / paying into a 4000% profit game.
AA
Pretty much this... I found the pricing of cartridges obscene, but the real reason of my switching to DE, was that the carts and electrics were destroying my face at every shave.
It was a "precision" single blade on the back of the head of a cart. that "enlightened" me as I found that using the cart. upside down for that single blade to do all of my face, I was for the first time in my life getting a decent shave, but it was difficult.
Having heard of DE from others in another forum as being the best thing ever, I decided to make the jump and give it a chance, heck I had nothing to lose and everything to gain. And I never looked back since.