Antiviruses. To install or not to install?

"The border is locked, but the enemy is already inside" - this is how one popular antivirus was described in the early 2000s. Anti-malware programs have been around for many years now, and users regularly resort to their help. At the same time, there are many stories online about how antivirus software is not really needed and does not protect against anything, and sometimes behaves no better than malware. Should we believe the gossip and rumors? Should we install it or not?