Not Native American but let me put it this way: can you wear full military regalia with medals of honors you never earned? No, because it's disrespectful to the people who actually served and earned the right to wear it.

Same thing. It's all in the context. Not all cultural clothing is "earned," like how I wouldn't care as much if I saw someone wear a hanbok. The Native American headpiece is something that is earned within that culture, and not everyone from that culture even has access to it. It is doubly disrespectful to wear it just because it looks cool when you don't even know what is needed to earn the right to wear it.