The internet is a public place
…or, at least, you should treat it as such. When moving through public spaces you observe common decency, you don't play music on a speaker, you make sure your cock isn't flapping in the breeze, and you don't take up immense amounts of space. The same applies online. You should understand that there are many other folks out and about on the 'net and you should respect their use of the space, and with any luck they'll respect yours.
What does this imply?
You should follow netiquette when online. A few things to avoid
Public means public
You should assume that what you post is both public, and could be tied back to your real identity. It's trivial to archive an entire discord server or Twitter DMs. It's generally not difficult to find the real identities of internet users, even those who use pseudonyms. Assume everything you post is going to be online forever. Once you hit post you have no way of controlling what others will do with that content.