can they be hacked
Anything on the internet can be hacked. Once you know what you're doing, hacking into company websites and computers is a cinch.
Are you sure with that?
You can't literally hacked all of the things in the internet thus you can collect information through bypassing a security. That's the reason why some of the social media accounts where being hacked but literally they're being hijacked and the information was being collected. Also, blockchain has an ultimate security, you can't easily hacked each wallet and control the transaction. The only thing you can do is decrypt but that's not very sure you can do it.
You can hack a lot of stuff on the internet through different ways, but I do agree that it is not possible to hack literally everything. It is not exactly a cinch to hack every website out there due to the advancements in security protocols. Most hacker groups usually have insiders to assist them to help perform the hack which is why these operations are seriously complicated and not easy to pull off.