Can artists make good money selling art prints?

Not many do. Even America's greatest photographer, Ansel Adams, had to give lessons due to his poor earnings from prints. Most artists have to make money from teaching and how-to books. Many artists have to do advertising or paint plates. It is possible to survive. For a single person without big outgoings. Some do prints on eBay or eTsy. As well as their own websites because they take a big commission and fees for things like listing etc are high (eg compulsory 12% turnover on advertising fees).

yes ofcourse.

Just need to find the suitable client and platform

Thomas Kinkade died worth   $70 MILLION. 

Not bad for painting houses with the lights left on. 

Some of them do.  Many don't. 

I don’t know about good money.  It depends how accomplished you are.  It’s a revenue stream that artists have available to them.