It all depends upon where and how you live. Had a professional monitoring system for 12 years while I lived in a heavily populated area and had a long commute. Along with the monthly bill, I had to pay for any repairs, upgrades, and changes. When I cut my landline I had to pay close to $200 to add the wireless ‘radio’ to the system. I had to buy my own back-up battery every 4 years. And then there are the contracts. I was lucky with the company I had because they let me go off contract for a year before I moved. Some companies are vicious at renewing contracts without customer approval then forcing buy-backs. My community required that residents register all monitored systems. They charged fees for false alarms. I never had any but it could get expensive. When I retired, I moved to a quieter area so I went with the DIY system. It’s easier to control and much less expensive. No contracts. So far, no issues.