I'd be less worried about some idiot in their garage than a rogue government or a well-funded terrorist organization. Gene editing can be cheap to do, but it remains expensive to do well. There aren't so many people successfully running wet-labs out of their garage, because there's a lot more equipment that you need than just the CRISPR. The biochemists I worked with last year were using some technique to program bacteria to make human eye lens proteins, but they screwed up more often than they succeeded, and we had an entire research institute worth of resources available to us.
Maybe there's something I'm not getting here, but I don't see how an easy gene editing technique alone makes this kinda thing available to everyone.