How do you make online friends? I’ve been on Reddit for many years and have rarely even DM’ed anyone. I’ve also tried apps like Boo but the conversations always fizzle out.

Mostly on technologies that enables people talking. My first online friends, were from using IRC; I even made local friends, I would never without using the online way. Then I made friends using simple emails to far away people. Next I remember I did a lot of friends using SecondLife, were i found out about "mein sonnenshein", a virtual friend i virtually married 4 times and divorce four times also (it was very cheap like 10 cents to marry and 25 to divorce, lol) and a lot of other good friends; last one i got it in a MMORPG where i saw a "beautiful" elf warrior and started talking to her, and it results she spoke the same language and were in another continent. There is been a lot of time over, but i still make contact with some of them. I would dare to say that the virtual friends were as good as the real ones, because in the end we are all humans and connected with language, and resonate in many ways.

Reddit hasn't really facilitated friendships (let alone the kind leading to real-life meetups) since the 2018 redesign at least; even before that the site was remarkably impersonal compared to any old-school forum.

Discord's not a bad way if there's a shared interest. I met some great people on a server dedicated to a hockey team. We'd all watch the game and blather away in chat. You get to know them after a while.

You have to join a more restrict community such as the FIFA PRO Clubs or the Rainbow Six teams or whatever is restrict and gaming thing . The general chatter/board where a plethora of people hangout such as reddit won't get you anywhere just like real life