Just like anyone can buy a battery powered saw or grinder. Since no security setup is secure against a thief with the right tools, the idea is inconvenience to the thief and to get them to look for easier targets than your stuff.

That's actually the case for having a U lock and a cable lock. While neither is particularly secure, it requires two different sets of bulky tools to defeat.

My kids have had two bikes parked 24-7 at a major university in an urban area for 3 years with no issues despite rampant bike theft. They use a Kryptonite U-lock (orange one) locked using the Sheldon Brown Method and they have their wheels, fork and seat protected with PitLocks. Zero issues despite bikes being stolen (routinely) within 25' or even right next to theirs. Is it foolproof? Of course not. Does it work? Obviously.

Their bikes are old (late '80's) high quality road frames with Campy or Dura Ace components, custom wheels, quality tires and quality seats. We have about $125 in security on each bike which is a significant percentage of the value of the bike. That said, their transportation is more important to them beyond the value of the bike and my hassle in having to replace it after a theft.

J.