It seems pretty useless and a waste of money for no actual impact.
Well, the alternative explanation is what you suggest (as I take it): it's
just vanity/dick swinging (they like the idea of owning something big and shiny).
Perhaps it really is nothing more than that - but then again, it seems to me that dick swinging is a poor explanation for something done by a
state (for an individual businessman, sure - yes. But we don't really believe in the idea that the "oil clubs" are owned by individual businessmen, do we?)
Like I said in the other thread, I recently had an interesting conversation with an expert on ME politics. She had a lot to say about so-called "sportswashing", and she partly dismissed the concept (as it's presented in its most simplistic form). But the bottom line: she thinks this is very much a "long game" thing. It's about normalization, establishing a presence in sectors that ordinary folk actually care about (sports).
Don't ask me to explain how that works on the details plane - I can't, I have no idea
exactly how they intend to make money from this, but it seems likely to me that this is their motivation (not dick swinging but something more traditionally capitalist, let's say).