It's true - I do. I've seen how the sausage is made, and I'm of the opinion that it's nothing to worry about. You can take from that what you will.
Windows 10 is definitely "safe" to use. There are multiple levels of overview/regulation that exist within the company, and the people who work here are very aware that what they are doing effects millions (billions?) of users. Even if you don't trust that, there are also fairly detailed regulations already in place by global governments to protect your rights that companies (such as Microsoft) have to adhere to if they want to continue to do business at a global scale. A non-trivial amount of work is invested into documentation/disclosure/user-facing opt-ins/outs for the above reasons.
It's also worth pointing out that the main reason to track user activity is for content suggestion/delivery. Companies such as Google and Facebook make the majority of their revenue from ads (in Google's case, 85%+). Conversely, Microsoft's main revenue streams are commercial licensing of Windows, Office(365), and cloud services. Microsoft has much less of an incentive to track your private/personal info, and much more to track the performance/reliability of their own software, which is exactly what the telemetry is doing.
At the end of the day, it all comes down to how paranoid you want to be about things, and how much trust you're willing to allow in exchange for convenience. E.g., even with open source, unless you are downloading and compiling literally everything on your system from the source repos, you still have no idea what is actually running. It's very easy to configure modern build tools to automatically insert/modify code during the build/package/release process. Beyond that, what about your hardware? Who wrote the firmware running on your WiFi chipset? Where does the chain of trust end? Do you really have the time to do everything yourself in order to be
completely sure, or would you rather, you know, go outside today?
That's not just tech, but society as a whole, which is what I was (mockingly) referring to in my original post. You want to keep a secret? Live by yourself completely off the grid. Anything beyond that and you are losing privacy. Two people can keep a secret, but only if one is dead, etc. But just imagine how stressful and shitty that life would be.
Anyway... grand scheme of things, Windows 10 is fine. It's been out long enough now that even if there was anything questionable going on, at least one person would have found it by now and raised a red flag. If you are actually concerned about privacy, there are other things you should be looking into wayyyyyyyyyyyyyy before this.