It’s not about building a sustainable profitable business, it’s about doing something that will be seen as so cool and edgy that you’ll be able to do it with other people’s money, and then cash out via IPO or sale before it all falls apart.
Then you can call yourself a serial entrepreneur and do it all over again!
Well, Millenials believe that profit is EEEEEEEEVIL.
So you see, it works for them.