Aside from the unpredictability of it all, per brclarke above, it is definitely worth paying attention to surroundings. I've only once had stuff stolen from a campsite in the USA, but in retrospect our camp was in a National Forest known for a preponderance of meth labs, visible from a gravel road, and we were gone all day climbing. Even so, the thieves just grabbed a couple of items from near the tent door--they were hurrying, and didn't want to get caught.

The above applies only to *human* theft; I've also had stuff stolen or trashed by mice, marmots, raccoons, ravens, and bears. IMO those are the real concerns while camping.

Personally, I try to leave stuff on my bike only when it's locked in hard cases. I also carry a cable lock for threading through pants, jackets and helmets when I leave them behind. I definitely wouldn't leave anything valuable such that someone could "just undo a few straps and walk away with my bags." That's why god gave us locking cables, bike covers, and Pacsafe steel mesh bags, not to mention accessory straps and rubber bungies to make theft more awkward than it might seem at first glance. I don't use an alarm because when I tried I routinely forgot and set it off myself.

The cardinal rule for traveling remains: back up all crucial information, and carry anything you can't afford to lose directly on your person--passport, license, credit and debit cards, cash, phone/camera/other devices. In the US and Canada that might mean in a daypack unless you frequent dangerous neighborhoods; elsewhere in the world it's often inside clothing in various pouches designed for this purpose.

Hope that's helpful.

Mark