Desktop app vs Website?

Been developing an algorithm thats largely dependent on data. That data needs to be updated on a regular bases (on my side). This leads me to thinking I need to change a monthly type subscription for the program I am making.

Initially I went with the Desktop app with QT. Does everything I want it to do but now I am not so sure. Are most developers aiming for web app instead of desktop app. Or trying to do both in parallel along with a mobile app?

As I am early in development I could look at the transition from desktop app to web.

Only issue I face is processing the data is CPU intensive so would need a server setup to match multiple customers running the algorithm.

I guess overall my goal would be to get as many customers as possible. Am I shooting myself in the foot by going desktop app only.