Malwarebytes

Not necessarily unless you are in the habit of installing malware on your computer. This is easily avoided by using a little common sense such as don't download from a site you do not know or trust, don't fall for scams as explained in Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams and don't download software from torrents and don't download adware. If the 15+ years I have been using Macs I have never had an issue because I follow my own advice.