^^^^That is why stealing is wrong! But so is parking in front of a fire hydrant and running through a shopping mall naked. The question is, which crimes are so bad that the perp deserves to die. If someone breaks into an occupied home, I can understand shooting them or whacking them into center field with a baseball bat.
But if you catch someone sneaking out of your house with some of your property, and you personally are not in danger-- they just want to run away-- are you justified in using deadly force on them to get your sh!t? Like, shooting them in the back?
Things that are not replaceable--rare books, family photos, souvenirs from trips, etc-- are not the things most thieves are after. Things that thieves want-- money, credit cards, TV's, cameras, cellphones, radios, laptops, guns, leather jackets, jewelry--are usually replaceable. It takes time and is a hassle, but you can get them again. I've been robbed of some very valuable jewelry and I was quite upset, but I have other jewelry.
The only things in my house I would risk my life to protect are my daughter, my husband and my doggies. If everything else was lost in a flood, theft or fire, I would be very sad, but if I lost my family, I would never recover.