So here's the thing: I'm the only player in our group who writes long, detailed backgrounds, and it's pretty easy for me since I write stories quite often anyway. I've had 3 characters with our current group, which consists of people I've known for years, and we've played together for almost a year now. I've noticed how I'm the only person who has ever asked anything about anyone's character. And when I say that, I mean in the style of being around a campfire and asking, "So how did you learn how to fight like that?" Or something related to their families. I avoid the latter in terms of one player because I know for a fact that the answer is always "uhh..uhmm..I don't know, does that matter?"
I'm absolutely fine with people not writing detailed backstories, but how on earth could I get them to ask something about my character? I already tend to make the weirdest or the most mysterious character I possibly can to make them interested, rather than creating stereotypes, but that doesn't seem to be enough. I'd be absolutely delighted to tell them all about my character's family, how he learned how to use magic and/or weapons, and all that stuff, since I spent all night writing it. It's kind of a bummer to never get to share those stories with anyone other than the DM. For what it's worth he really likes them.
Best Answer
First, you can't make people care about your backstory if they aren't interested in that sort of thing. I know it is frustrating, but in RPGs, there are so many different things people want out of the game, and not everyone cares about the backstory. Heck, some don't even care about the story. If they are just looking for a dungeon crawl or murder hobo game, they might not be interested in the backstory of your character.
Second, share it with your DM/GM/StoryTeller. Your DM may, or may not, wish to tie events to characters' backstories.
Third, you could (out of game) look at tying your backstory in with another player's backstory, so at least to that other player there is something to be gained from those questions. Especially if you work with/through your DM/GM/StoryTeller – maybe you know the answer to one of the questions one of the other players is seeking.
Lastly, backstory informs roleplay. Maybe it isn't necessary to fish for people asking, or to beat people over the head with the backstory, instead just roleplay the character thinking about what they would do in each situation, and maybe backstory points will come up. "Oh, DM/GM/Storyteller, do I know anything about this symbol from my time studying while at the temple of ... ?" Etc.