There's a reason "slide into the DMs" is a saying: https://www.dictionary.com/e/slang/slide-into-the-dms/
There's a reason "slide into the DMs" is a saying: https://www.dictionary.com/e/slang/slide-into-the-dms/
It's also worth mentioning that it's very common for companies and celebrities to use Twitter DMs as a sort of "customer support" where they specifically ask people to send them private information via DM. I've seen tweets from utility companies where they say "Please send us a DM with your account number and we will look into your issue" [0], for example. There's the possibility for valuable information there.
0: https://twitter.com/comcastcares/status/1284358479835258881
Edit: The person I would consider my “best friend” we chat 100% over Instagram DM. This is a person that I can invite myself over for dinner to, that’s how close we are in case you feel like assuming we must not be good friends if we don’t just call each other or whatever. Another of my good friends, we switch between iMessages and WhatsApp I’d say 50/50, just depending on if I’m already in WhatsApp talking to someone else and decide to message her too or not.