Dave McClure and his team of investors started the seed fund and accelerator program 500 Startups in 2010. At a demo day in San Francisco on Thursday, entrepreneurs from 500 Startups' sixth accelerator class presented their ideas to a room of potential investors.

At the same time, McClure and his team celebrated a milestone of their own in June: Their 500th start-up investment. He shared his thoughts on the accomplishment--and what he's learned in three years--with GigaOM's Eliza Kern. The full interview is worth a read, but here are some highlights. 

First impressions stink.

As an early-stage investor, it can be difficult to weed the successful start-ups from those destined for failure, McClure said. "Your first impressions are not always correct,” he says. “It often takes six to eighteen months to figure it out. I mean, we often figure out what doesn’t work within six months. But genius emerges more slowly.”

He added: "A lot of VCs like to think they know exactly what’s going to work, like, ‘Oh, I remember when they were so awesome and I was so awesome picking them.’ But the more we do it, the more we realize that we’re wrong a lot. That’s why we take more bets, and pretty consistently, we’re better able to identify wins."

Not everyone can be a winner. (And that's okay.)

Even though a few 500 Startups companies like Taskrabbit and Wildfire have attracted the spotlight, not every company that goes through the program will be a success.

“Everyone who’s an entrepreneur is irrationally optimistic that they’ll be in the top 10 percent," he said, adding that those who realize they won’t be in the top 10 percent--but look at the program as positive learning experience and springboard for future projects--are the entrepreneurs who do best.

Silicon Valley is an attitude--not a cure-all.

Some founders move to Silicon Valley expecting it to be a place of otherworldly innovation and creation. "Silicon Valley is a magical place, but it's comprised of people from somewhere else. It’s more about the attitude--it’s not so much where people are from," he added.