To self-proclaim as a thot is to be self-assured in your sexuality. Using it to describe yourself is a form of power; reclamation of something once used to insult you (or people like you) and removing it from the hater's lexicon.
Is it controversial? I think it's not unlike how LGBT+ people have adopted "queer" as a positive, not a negative, identifier. However, the more conservative among us might see the reformation of the word ho as questionable – spurring the same debate as the reclamation of the n-word in black and brown communities.
To self-define as thot is not gender-specific, which helps in devaluing it's misogynistic history. Both women and men will call themselves #thots on social media, particularly when posting a sexy photo and being honest that you have no shame about doing so. It's sometimes actually used in jest so online trolls don't have any power to abuse you.
This isn't to say it's okay to call somebody else a thot. To be safe, it's really only something you can use for yourself, e.g. with a selfie. To say "that ho over there" is otherwise derogatory when you're commenting on somebody's appearance or their sexual prowess.
However, I'll call my friends (and people I follow online) thot or thottie, but I use it as a term of endearment. Akin to the way "b**ch" is sometimes used (it's another reclaimed word for certain groups).
I consider it a compliment to post a comment such as "thot werk!" or "thottie!" on somebody's selfie, especially when accompanied by an appropriate emoji like the salsa dancer. If they're the kind of person who doesn't take themselves seriously and would self-identify as a thot, it's confirmation of how good they look, and how much of their sexuality they are owning.
So can YOU use thot?
If you're part of a group that would have been targeted with slurs about your sexuality (e.g. women and LGBT+ people), and you want to reclaim it for yourself, it's yours for the taking. If you want to call someone else a thot, you should also already be part of one of those groups (and only be using it as a compliment, not in a derogatory way, in situations where it will be received as such).
For anyone else, you might want to steer clear of commandeering this term. It could be considered sexist, misogynistic, predatory, or as sex-shaming. There will still be many people out there who, unlike me, will be offended by the word thot even being in existence.