I can create a business that does things only in computers and use the funds to buy other things only in computers, how is that different than a game?
Games are life with an easy mode, and many things which are "not real" are just as fulfilling as things that are "real".
Accumulating wealth is mostly just a game anyway once you have the basics covered, and when you start thinking about it too hard everything is equally unreal in that nothing has any worth outside your own arbitrary values.