Run a Bitcoin mining rig. This is a popular way to make money with VPS, but it can be quite expensive to get started. You will need to purchase a powerful VPS and pay for electricity costs. However, if you are able to mine enough Bitcoin, you can make a significant amount of money.
Host websites. You can rent out your VPS to businesses or individuals who need to host a website. This is a relatively passive way to make money, and you can charge a monthly fee for hosting.
Run a proxy server. A proxy server is a server that acts as an intermediary between a client and a server. This can be used to hide the client's IP address or to access websites that are blocked in certain regions. You can charge businesses or individuals for using your proxy server.
Run a file sharing service. You can allow users to upload and download files from your VPS. This can be a good way to make money if you have a lot of bandwidth.
Run a game server. You can host a game server for a multiplayer game. This can be a good way to make money if the game is popular.
These are just a few ideas for how you can make money with 20 VPS. The amount of money you can make will depend on the specific services you offer and the amount of traffic you can generate.