UPDATE: Avast is winding up their data selling subsidiary after their stock prices got hammered following this news.
This is pretty much the norm for most freemium apps and services now. Most users simply do not understand these practices. The ones who do and highlight it are fighting a losing battle.
Speaking of anti-malware, there really aren’t many ethical options. Open source solutions like Clamwin are utter shite. Windows 10 users should stick to Windows Defender. Microsoft already collects your data in return for free Windows 10 updates, so you might as well make the most of it. Data collection aside, Windows Defender is pretty darn good, despite what many security experts on the web will tell you. They make money from affiliate links to paid security products, hence the complaints about Defender – a completely free product (not knocking others’ way of earning money, but this is something users should be aware of).
macOS and Linux distributions don’t really need anti-malware, as long as you install the system updates and stay away from shady torrent and warez downloads.
Besides anti-malware, a very important component of online security are ad blockers. They block a ton of domains that serve malware and adware. uBlock Origin is my favorite ad blocker for all major desktop browsers. iOS has good “content blocker” apps. Google doesn’t allow ad blocking apps in Android’s Play Store, but browsers like Brave and Firefox do provide ad blocking features.
There are also ways to configure system wide ad blocking on desktop OSes (Steven Black’s host files, dnscrypt proxy) and rootless Android (DNSFilter). I might cover them in detail another day. Which, to say, is probably never.