1: Yooha's like 5 years old... she doesn't know any better
2: she just thinks that there's a nice lady that'll give her something cool - there are nice people in the world too, you know
3: She probably has a lot of faith in her dad. He's literally one of the strongest people on the Earth. No one can harm her while she's his daughter. 
So, no, it's not just Yooha that was a stupid little brat. She was actually pretty smart considered her age and she also declined the "gift" to start with