If someone were to invent a cure for cancer...

[Ban my account ffs!]

Invents a cure for cancer?  Unlikely.  Discovers one?  Sure.

It is immoral to deny somebody treatment of cancer if it is available.  Cancer is a disease that can affect anybody.  Why should only the rich be cured?

[Ban my account ffs!]

There will never be a single cure for all cancers, but yes, people that invent or discover new medical procedures, drugs or whatever should be able to get as much money out of it as he or she can, just like any other industry.  We do want medical advances to keep coming at the same speed right?  If you limit the funds these people can make from their labor in time you will see less capital investment, fewer smart people doing the work and fewer new technologies. 

If it means more to you to give everybody decent medical care than it is to advance medical science further for everybody, well, I guess that's your choice.  It's an awfully shortsighted one, but a lot of left wing/statist positions are.

Except you aren't advancing medical science for everybody.  You're advancing for the person that discovers it and the group of people that can afford it.  You are no longer curing cancer.. you are simply allowing those that can afford it to live without it.

[Ban my account ffs!]

Obviously they will discover one quicker if they are motivated to do so by making money

How is that obvious?

I don't think it takes much to realize that people need some kind of motivation to drive them

Like perhaps being known eternally as the Joe who cured cancer?

I'm sure you could become plenty rich while still providing care to everybody that needs it,  especially if the cure for cancer comes from the sources that they're currently studying.  (hint, the tree in your back yard)