N of 1, but “cocky arrogant megalomaniacal behavior” and a goal of polarizing people into liking and disliking you strikes me as suggesting disrespectful behavior. Obviously I’ve got no idea what you’re specifically contemplating, so this is just explaining how your word choice produced my interpretation. Since as you say assuming that you’re normal is a reasonable default assumption, I’m assuming my reaction to this is normal.

I don’t know enough about building a large audience online to have things to say about what sort of online persona gets and sustains mass attention. So if that’s your primary focus then please ignore that part of my response. I was more thinking about settings like work, parties, school, and so on.

Your point that “personality is more mutable than people think” or is only immutable by definition is well taken.

RE being genuine as a nonconformist, my guess is that everybody has a few quirks that they have to be careful about, that limit their ability to be genuine. Some people probably have much more than others.

I don’t know that avoiding ruffling feathers makes you broadly less genuine. Maybe there’s some skill in creating “safe space” to be yourself, by choosing friends, words, and settings carefully to strike the ideal balance between saying what you want to say and having the social outcomes you desire.

But as a contrast, I think that in my own life, pursuing my career goal required tremendous, sustained convincing of other people to accept my decisions and stop criticizing me constantly. It could easily have stopped another person in their tracks. And I still don’t have the absolute freedom to spend my time and energy as I’d like all the time. There are many pressures to participate in social interactions where my freedom to do and say what I am most interested in are heavily constrained.

So perhaps you’re right. Maybe we are far, far more constrained from being genuine than we think. Maybe a greedy pursuit of exactly what we believe and desire would lead to a radically different lifestyle, and the frustrations and inhibitions that most people accept as routine are a consequence of a grand coordination failure. Of a prioritization of pre-existing social ties for their own sake, and a social unease with people who too readily change and pursue the unusual.

And maybe being cocky, arrogant, and megalomaniacal, being an extremely self-referenced person, is crucial to achieving that. It’s not enough to be confident when you’re alone. You have to fight for your freedom, every single hour of every day. Politeness, respectfulness, and kindness are important as lubricants to let you glide through the grinding gears of society. But if you try and pursue them too much, you wind up subservient to codes of polite behavior that will chain you.

That’s all very vague, but I do think it’s an interesting topic. At this time in my life, I find myself giving up on many other forms of “brave heresy” because I have to sustain the form of unorthodoxy that I think is most important of all. I’m spending my weirdness points wisely.

I have a sense that I have a limited budget for dealing with impositions by other people. I spend my reserves carefully. I think that the more I fight, the weaker I’ll be, and that as Sun Tzu counseled, the best form of generalship is to avoid fighting at all.

The vibe I picked up from your post is maybe that “fighting” strengthens you somehow, or builds you up. The losses are trivial, the gains tremendous, and people should fight often.

Without very specific details of where and how, I’m not prepared to agree with that as a sweeping approach to life. I think that cooperation, gentleness, reserve, praise, and occasional signals that show you have powerful forces under your command is a better approach.

I think it achieves much of what brash cocky arrogance achieves, in terms of making you seem attractive and interesting, but also allows you to achieve better long term results. Certainly if I was in a position of power, I would choose to hire the person who showed “graceful power” than “cocky arrogance” every time. Same for who to date, befriend, vote for, read, or collaborate with.

Why not? You want to let people start using words with very negative connotation to refer to whatever they want? In practice, that's how "toxic" is used; whatever people want it to mean, typically when the thing in question seems socially inconvenient for them.

Imagine you acted in accordance with your own logic and best judgment of probabilities in the way you normally do, in a way that you see as nuanced with respect to the moral culture you have lived through and continue to live through, and suddenly someone wants to paint it as "fascist" without understanding the basis at all. Do YOU think your behavior is fascist? Probably not. Words should not have such power without robust moral reasoning driving them, otherwise it is bound to bring dogmatic irrationality to situations that robust moral reasoning would have something to say about.

It is possible that OP has an unusually operationalized usage prepared for "toxic," but when I made my first comment on this post, I should bet against it.
Related: The Anti-Jerk Law by Bryan Caplan