Now this is speculation. I am not saying this is true and I have no evidence for this. On the other hand nobody has evidence against this either.
So now that that's out of the way, I would like to share my headcanon. Now I want you to think about Ice King's crown. What do we know about it? almost nothing. We may know that it was once owned by a dock worker and that it is also what caused Simon to go insane, and that it has feelings, but we don't really know anything about the crown itself. Who made it? Was it always a crown? Is it REALLY evil?
So I am going to answer these questions to the best of my ability using as much logic as I can and how little things that we know about it.
Who made it? This one is kind of a blank. Wwe don't know much about pre-mushroom war and how it was. We do know though from the crown that there was magic in the past at some point. THere was also the enchiridion but the crown came first.
Was it always a crown? Now that is kind of a simple question for me. I don't think it was always a crown(I am referring to the spirit and personality of the crown. Not the item itself.) If it was then why would it have feelings this deep? WHy would it care so much about another living thing? I understand that someome might bring up the thought of "oh hey! People care about animals and they are different." and that is true. I just feel that this crown's feelings for tis one perspn is so deep that I don't think two different species have ever shared (I mean how many guys can you name that would freeze the world in blind greif over your death? I thought so). I feel that it was a human at one point. I have no idea who it was or what is was but now it's a crown and it has to deal with it.
Is it really evil? This one kind of ends at a cross road. It is a matter of opinion and right now nobody is right or wrong about this. It's just that most people lean twords the evil side when they think about the crown. I for one think that it just might be good, but of course I have no evidence, but I do have a senario in which it could happen. What if the crown was trapped there? Trapped there against their own will. They obviously didn't want to be trapped there forever (maybe it had a meaningful life before then) and they decided that the only way to get back was to get energy. To bad they couldn't get energy unless they came in contact with the most powerful part of an item. So what a day it must have been when Simon came by and decided to buy him (or her. Still debating this but I am calling it a guy for now) and decided to wear him. He absorbed all of the power that he could and made SImon go insane ( I'm also not sure if he knew what he was doing) and then it catches up to the present. SImon is going crazier as the crown takes power (and gives ice powers in return).
Please do not be afraid to comment and tell me what I did wong or what an stupid idea this is (but please don't go on and on about it because that is just annoying). Thanks for reading and tell me what you think about the crown.