Is this legal?

[ChessMan]

I agree. I am a computer scientist and can judge the feasiblity of a project such as this.

To collude undetected would be very hard. It would take so much work that it's not worth it.

There's so much more opportunity in creating software that people will pay for. This sort of project would be very low on the to-do list of any software developer.

The main reason is collusion (without being detected) gives a very small edge. The colluders can't collude too much because it will become obvious very quickly. I'm sure the sites monitor how you play your hand, who you play with etc. Collusion is a big threat to their business model so they take it seriously.

As with most things, to make really good money, you're better off doing something more ethical. If you make big money at collusion, you will get caught.