There is a number of companies that make what's called 'app-scripts'.
One is appdupe.com there are a couple of others.
Basically they take X-like-Y business ideas that demonstrated, nominally, their worth (in either solving a business problem, or attracting investors).
And they just duplicate those models -- uber-like, tinder-like, etsy/ebay-like, and so on.
They generate the source for apps, backend services, etc --- you just give them your twitter handle, name, logo, contact, fb page... whatever.
I also read when researching this, that some of them produce 50 apps per week.
Apparently, again 3rd hand info, that their services start at 10K usd and go up from there....
I have no idea about the quality, may be bad and may be they they will end up charging 10 times more what you though initially...
So imaging that people are not shy of duplicating a business idea and just applying perhaps to something else, or just a different geographical region....
It is definitely not pointless building software that already exists.
I would say go for it...
Either of 3 things will happen
a) you are successful and completion fails
b) they are successful and you fail
c) you are both successful
in all 3 scenarios -- end users seem to be benefit.