Some people seem to think that the only reason someone would want to encourage new people into fandom is because it will create bigger conventions, be good for fandom, etc. These things may happen, but they are only side effects of welcoming in more people. I could do a big diatribe on growth versus stagnation. I could talk about how it's really easy to say we have enough people coming to cons when you're one of the folks who already attend and you know you're welcome, but it's not relevant to why I want to see more newbies in fandom.
I want to see more new fans for their sake, not ours.
Maybe it's because I've been doing 'so it's your first con' panels for over a decade, but I've seen a hell of a lot of people at those panels who turned up knowing
no-one, not a single person at the con. Some of them stick around, but many do not, and not all of those that leave can be fobbed off with the oh-so-easy 'it just wasn't for them' comment.

The whole 'most people are drawn into fandom with their friends' argument is a really easy one to make when you're surrounded by your mates, or that is indeed how you found fandom. I've talked to people who spent an hour or more outside a club or convention, absolutely terrified about going in because this was it! This was where they finally hoped to fit in, be welcomed, find people like themselves. They stayed outside because they were scared that they'd find that they wouldn't even fit in here, and if they didn't fit in here, that's it, they really were the loser, freak, and weirdo that their family and the people at school or work thought they were.
I had a cold start, knowing nobody, and it was absolutely terrifying. I spent a fair while outside Space Age Books before going in. And my very first experience of another fan was the gruff guy at the front counter being, well, gruff with me. Not unfriendly, not nasty, but my self esteme was low, and I was shy and nervous enough that I nearly left then and there. I already felt like an outsider who was at best to be tolerated. It was touch and go, and rather than walk up the stairs at the back of the shop to go to the Melbourne Science Fiction Club, I nearly ran out the front door.
If I had I would have missed out on a range of friends and experiences. Would never have done song-vids, run conventions, written fiction, gotten into 3D animation, had the friends and lovers that have enriched my life. I wouldn't have met Sharon.
So why wouldn't I, in all good conscience, want to give other people the same chances I've had?
How many people have been lost from clubs and cons over the years? Where their first experience was their last? It's not just people we lose when this happens. I want to see more new fans for our sake as well.
Every person who never attends or returns represents the loss of potential friends, lovers, con-runners, writers, editors, artists, directors... For all the good or bad they may have done our lives, the community, or the genre, they may as well have never existed.
There will always be people who are lost to us. Some people are too sensitive or scared, some bad experiences are unavoidable, and we can't be held accountable for every lost fan. I don't talk to every new person at a con, and I sure as hell don't expect others to. But the less we do to encourage these people, to try to find ways to make things that little bit more welcoming for them, and the more we sit on our collective arses saying, "they'll find us when they're ready," or "someone would bring them in anyway," the poorer our community becomes.
If you don't believe that, then think on this - If I had chosen the door instead of the stairs...
No Mitch, and no
Mitch? collections.
No Pancakes at Carillion.
No Continuum conventions.