Whether the loss is property, memories, or life, having a home security system can prevent those losses entirely, or prevent them from being severe. As soon as your security system attached fire alarm goes off, the fire department, as well as yourself, are notified. The chances of life, your possessions, and ultimately your home being lost are decreased significantly.
A burglar can take your stuff, but a fire will take everything
Significantly better than just an alarm you buy from the store. Like the Fire alarm, if carbon monoxide is detected in your home, the authorities are notified, bringing you help immediately.
Even if your alarm is not set, most systems will tell you when a censored door or window was opened.
Letting you know immediately that your home has been invaded. As well as scaring away any but the most determined of invaders.
Many peoples houses get broke into
Your local law enforcement will be on their way to help you when your alarm goes off
If it takes 10-15 or more minutes for police response, then the "protection" is useless!
When your alarm goes off, your home security company will call you, immediately, if there is no answer, or if you answer that someone has broken in, the alarm company will call the police for you. When your fear and adrenaline is spiked, sometimes it's hard to focus on what you need to do.. They do it for you.
They're so slow in arriving, this may not be an advantage at all. I know too that many of them don't even walk around the house---the most they do is a drive-by.
Actually, most burglaries in the US occur in daytime, when the criminals don't know you if have a security system, and with a swift kick to the front door or through open or unlocked doors and windows. And, it happens all too fast foor law enforcement to stp them usually, since they're in and out in just seconds to a few minutes. Locked, sturdy doors, watchful neighbors, and a dog are better than any alarm against burglaries.
A yard sign makes them look elsewhere
They can also be good as a back up system, or for a closet with valuables, or a basement.
If some sneaky thief thinks they can bypass your door and window sensors by breaking your windows, they are going to be surprised. These monitor vibrations, and set the alarm off accordingly.