Visiting only reliable sites and downloading programs from official sources will not give the full guarantee of the protection from the malware and other viruses. You will never be safe if you go online without an effective and reliable protection.
You can never be too careful
If you are thinking about whether or not to use the antivirus software, you can think about whether or not you will ride a motorcycle without a helmet. Even if you are careful, there is the likelihood of an accident. Malware developers usually clearly understand what needs to be done in order for the threat to be successful. That is why malware exists and causes damage to people.
Something is always better than nothing
If you do not use any protection at all, you can at least enable Windows Defender. However, the effective third-party antiviruses are still relevant in 2018. Their main task is not only combating traditional viruses but also preventing various types of attacks that have the goal to get control over a computer or to steal confidential data. You can use some simple software or more advanced, like Bitdefender GravityZone Advanced Business Security .
It sounds frightening, but the active use of digital devices by users leads to the fact that the threat remains real. Ultimately, the choice of protection solutions and security strategies depends on you. Just do not think that a potential attack will not touch you. Everything can be exactly the opposite.