With coolers, people would take them to use, not for resale. It is different with cordless power tools which I keep inside my vehicle always..
With meth'heads, it's about craigslist, ebay, pawn shops, etc.
I am considering one of the smaller ones that I can easily place inside the cab of my truck. That is not an absolute protection obviously. People with pickups often have stuff like bolt cutters. I carry a small one myself, but not for stealing stuff. It is a last resort on some jobs and getting approved access. Waiting 4 or 5 hours for someone to open a door is not something I am patient with when it was supposed to be open to begin with. I actually do not lock my tool box on the back of my pickup. It is too easy to break into those and I don't want the damage. I just don't keep anything particularly valuable inside.
Yep, drug addicts will do a $100 damage to your toolbox to steal a $10 item at retail. Putting things "in sight" in your pickup is a great way to get a window broken. Tools like weed whackers and chainsaws need to be in a locked "box" that is secure if you are not with them constantly (think lunch time thefts, going in to get a cup of coffee and to pay for gas...).
Then there are the general "drive by" thefts with losers out cruising for a quick buck.