It's difficult to measure "could-have-beens," so research is mixed on how well home security systems actually deter crime. One expert told The New York Times that he's seen little evidence of risk mitigation with things like alarms and locks, while the NCHSS boldly claims that homes without any kind of protection are 300 percent more likely to be burglarized. (The FBI’s Uniform Crime Reporting Program defines burglary as "the unlawful entry of a structure to commit a felony or theft," FYI.)
Even the culprits themselves are divided. Some convicted burglars surveyed by an Oregon news station in 2017 said they weren't daunted by security system signs and alarms, which could be disabled or avoided, but most would steer clear of a home with a big, loud dog. Yet 60 percent of burglars surveyed for a frequently cited University of North Carolina survey several years prior would find a different target if they saw an alarm on-site.
These findings should also be considered alongside the fact that burglary rates have seen a sharp decline over the past decade; they only counted for about 16 percent of overall property crimes as of 2019. (That also includes motor vehicle theft and arson.)
The one thing everyone seems to agree on is that most break-ins occur when people aren't home — and in that case, a home security system serving as your eyes and ears from afar can provide invaluable peace of mind.
As an aside, installing a home security system may also qualify you for a serious discount on your homeowner's insurance, which certainly doesn't hurt. Contact your insurance provider to learn more.