HI @Anonymous,
I'm sorry to hear that this is happening! I know you are probably getting sick and tired of trying to uninstall/reinstall the software, but with Fusion 360 we actually have a clean unisntall procedure that wipes all installation/update files from your computer manually. Realistically since you said you have been using the software for 1.5 years without a launch issue, my guess is something might have happened during an update and it was not updated correctly - just a guess however. By cleanly uninstalling it will give us a fresh slate to start from and we can continue troubleshooting from there if that doesn't work. The guide to do a clean uninstall can be found in the link below:
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-do-a-clean-uninstall-of-Autodesk-Fusion-360.html
Make sure to follow all the possible steps you can and please note that the folder paths are by default hidden so you will have to enable hidden folders in order to navigate to those paths. Also, it may tell you to delete some folders/files that do not exist on your computer. That is okay, just delete the ones you can (you still should be able to delete most of the ones it tells you to). Then, before redownloading Fusion 360, make sure that in your Task Manager or Activity Monitor that streamer.exe is NOT a running process. If it is make sure to kill it.
If the clean uninstall/reinstall does not work I will have to take a peek at your log file to take a deeper look into what is going on. You can use the following guide to locate your installation log file:
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/Unable-to-install-Fusion-360-Error-How-to-locate-the-installation-Log-File.html
Thanks,
James Youmatz
Product Insights Specialist for Fusion 360, Simulation, Generative Design