Credit cards? Yes, a tool. I don’t like to carry cash. I’ve had a credit card since I was 18. It’s great for establishing credit, you just have to be careful. My husband and I use it routinely, but we pay off the balance every month and never purchase more than we can afford. Meanwhile, our cash is sitting in a money market account and accumulating (a measely, but still it’s something) interest the whole month. There’s a lot to be said for being an adult and having some self control. If you know you’re not that kind of person, then go with cash.
Why not take your money out of money markets and put it in dividend paying stocks like Ford? They pay 6-7%. There are several strong companies that give similar returns. Beats 0.5%. Spread your money out over several.