I share their opinion, we're going to run out of resources on Earth, we already know it. One thing we're not good at is reining in our consumption. Once we've been shown what we can have, we don't like giving it up. Rather than do that the human race is far more likely to just think around the problem. The easy solution is to just go get some more resources. Asteroids are a nice, easy source of many, we can even drag them back to Earth to make mining easier.
I'm not sure it'll be the spur to get us into space, there's already plenty of people on that track, but it's going to take billions to get us from a commercial launch sector to a commercial human launch sector, and asteroids may provide that wealth (without the need for humans to start with).