Hi Paula!
I'm sure everyone has/ or is having this problem. When we first began asking friends and family about having a DW, he heard a lot of negativity. My mom said I was crazy, FI fam is still complaining about the costs, and ou can even find a thread that I started where I vented about my brother and SIL giving me a hard time about it. But little by little everyone is coming around. My family is so excited because we are (hopefully) going to have a huge turn out, approx 150ppl.
Give it time. Once they start hearing the details and seeing that its all coming together, they'll come around.