You can do all the privacy measures in the world, but if the people you talk to are using spyware then it's all out the window. (literally Windows, get it?)
This video breaks down some of the basic reasons to switch to Linux so you can convince your friends: https://video.simplifiedprivacy.com/why-linux-beats-windows/
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
These exist but often you can avoid them by using alternatives. I recommend not supporting LInux-hostile companies/services at all. Problem solved. This problem will continue to exist as long as Linux has low marketshare. So, the answer is not moving away from Linux, but rather to it, so that companies can't ignore Linux users anymore. Also, using Linux has many advantages in termss of user control/agency, privacy and security.
That's nonsense, there is no "true way" to use Linux. It's an operating system and there are distros which abstract a lot of lower level stuff away just like Windows or OS X do (e.g. Ubuntu, Mint, Fedora, OpenSuSE, ...) and there are distros which don't (or which simply don't care about including such things) and thus are considered more "for advanced users", where more stuff needs to be maintained/configured by hand and where less GUI-based tools are available by default. Some people actually like that sort of minimalism and the increased control, but of course it's not for everyone.
Also, if he has trouble with the commandline usage, then it doesn't make any sense for him NOT to use e.g. Ubuntu. Because then he obviously needs the "hand holding" of an "easier to use" distro like Ubuntu. So he shouldn't complain about it. But this is not meant to disrespect the accomplishments of Ubuntu. The most popular OSes/distros are theones which are easier to use and which abstract a lot of things away. Because otherwise, it'd just be a distro for more tech savvy people, period. Then again, if he's a dev he should in theory be more than tech savvy enough to use Linux as a daily driver.
I recommend using the Flatpak versions of GUI apps (in general). It's very easy and it's a trusted source to get tons of applications from. Although for Discord in particular, I don't reocmmend it, I'd just use the web version tucked away in a browser (ideally sandboxed) without too many permissions on your system. Because Discord is spyware, so it's best to keep it in check, if you need to use it. Running it in a browser automatically limits the amount of data they can gather about your system.