The universe, [Stephen Hawking] points out, has 100 billion galaxies, each containing hundreds of millions of stars. In such a big place, Earth is unlikely to be the only planet where life has evolved.
“To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” he said. “The real challenge is to work out what aliens might actually be like.”
The Times is overstating what Stephen Hawking said, but nevertheless, he’s arguing from incredulity. Just because the number of galaxies and stars is large doesn’t guarantee there are aliens. It doesn’t even make it likely. There’s simply no way to know at present how likely it is that we are alone.
As for the rest of the argument, it’s not much better. Any species of alien that has mastered interstellar travel will have perfected nanotechnology. Resource limitations won’t be a problem for them, unless you’re talking about pure raw material such as carbon. They’re not going to be running around the galaxy raiding planets for hydrocarbons.