Can I use the hats somewhere else, even for commercial use, or are they copyrighted?

No.

Being able to download a file does not necessarily give you the right to use it for your own purposes. You have to be able to download an image to view it; if that was the case, creators would lose all rights as soon as they uploaded a work to the internet.

Unless explicitly stated otherwise, Stack Exchange owns the copyright and reserves all rights not explicitly (or implicitly, in limited cases) granted to you. Quoting from the site's Terms of Service:

All materials displayed or performed on the public Network, including but not limited to text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, and animations (collectively "Network Content") (other than Network Content posted by individual "Subscriber Content") are the property of Stack Overflow and/or third parties and are protected by United States and international copyright laws ("Stack Overflow Content").

[...]

Other than as expressly set forth in these Public Network Terms, you may not copy, modify, publish, transmit, upload, participate in the transfer or sale of, reproduce (except as provided in this Agreement), create derivative works based on, distribute, perform, display, or in any way exploit any of the Network Content, software, materials, or Services in whole or in part.

Can I use the hats somewhere else, even for commercial use, or are they copyrighted?

No, you can't.

Being able to download a file does not necessarily give you the right to use it for your own purposes. You have to be able to download an image to view it; if that was the case, creators would lose all rights as soon as they uploaded a work to the internet.

Unless explicitly stated otherwise, Stack Exchange owns the copyright and reserves all rights not explicitly (or implicitly, in limited cases) granted to you. Quoting from the site's Terms of Service:

All materials displayed or performed on the public Network, including but not limited to text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, and animations (collectively "Network Content") (other than Network Content posted by individual "Subscriber Content") are the property of Stack Overflow and/or third parties and are protected by United States and international copyright laws ("Stack Overflow Content").

[...]

Other than as expressly set forth in these Public Network Terms, you may not copy, modify, publish, transmit, upload, participate in the transfer or sale of, reproduce (except as provided in this Agreement), create derivative works based on, distribute, perform, display, or in any way exploit any of the Network Content, software, materials, or Services in whole or in part.

No.

Being able to download a file does not necessarily give you the right to use it for your own purposes. You have to be able to download an image to view it; if that was the case, creators would lose all rights as soon as they uploaded a work to the internet.

Unless explicitly stated otherwise, Stack Exchange owns the copyright and reserves all rights not explicitly (or implicitly, in limited cases) granted to you. Quoting from the site's Terms of Service:

All materials displayed or performed on the public Network, including but not limited to text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, and animations (collectively "Network Content") (other than Network Content posted by individual "Subscriber Content") are the property of Stack Overflow and/or third parties and are protected by United States and international copyright laws ("Stack Overflow Content").

[...]

Other than as expressly set forth in these Public Network Terms, you may not copy, modify, publish, transmit, upload, participate in the transfer or sale of, reproduce (except as provided in this Agreement), create derivative works based on, distribute, perform, display, or in any way exploit any of the Network Content, software, materials, or Services in whole or in part.

Can I use the hats somewhere else, even for commercial use, or are they copyrighted?

No.

Being able to download a file does not necessarily give you the right to use it for your own purposes. You have to be able to download an image to view it; if that was the case, creators would lose all rights as soon as they uploaded a work to the internet.

Unless explicitly stated otherwise, Stack Exchange owns the copyright and reserves all rights not explicitly (or implicitly, in limited cases) granted to you. Quoting from the site's Terms of Service:

All materials displayed or performed on the public Network, including but not limited to text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, and animations (collectively "Network Content") (other than Network Content posted by individual "Subscriber Content") are the property of Stack Overflow and/or third parties and are protected by United States and international copyright laws ("Stack Overflow Content").

[...]

Other than as expressly set forth in these Public Network Terms, you may not copy, modify, publish, transmit, upload, participate in the transfer or sale of, reproduce (except as provided in this Agreement), create derivative works based on, distribute, perform, display, or in any way exploit any of the Network Content, software, materials, or Services in whole or in part.