I read about VPS again and again, but is it really necessary to run the secure node on a VPS or can I also just run it on my home cumuter?
You do not have to run a secure node on a VPS. You can run it on a home computer. To be more successful, make sure:
1. port forward on your home firewall/router ports 9033 and 19033 to your computer
2. Run it on a 64 bit operating system, linux preferred
3. Buy a domain and create a fully qualified domain name that points to the ip address of your home firewall/router
4. Run the secure node tracker and put the ZEN in the locations you need to for operation.
The problem with home computer, you are exposing your IP address to everyone, and you probably have some crypto wallets there too.