This method is not without possible risk but it worked on my system. Do so at your own risk and I highly recommend you back up your drive in case you need to restore it to its original state. I don’t know if a system “restore” in Windows 10 will work.
Check your version of Windows 10 (the build number). I believe MS says you need 1904 which is what I had but I couldn’t install MSFS. I had to download and install the MS Windows Upgrade Assistant. The “Assistant” allows you to install the latest build version.
After I ran the assistant and upgraded to build 2004, MSFS installed.
If I had known MSFS was going to cause so many issues, monitor everything I do, and grant access to every file on my PC I would have never installed it let alone purchase it. I wish I would have requested a refund. I will not make the same mistake again with any MS product.
Anyway, hope that helps. Good luck!