The demand is absolutely elastic to price, every time the club lowers the prices for games like this it always sells much better (See Huddersfield last year, and Fulham the year before). This game will hopefully be no different, as its way too early to declare that it hasn't sold out, and once it gets onto general sale I'm sure plenty more will sell.
When calcuting how elastic PED is for any good or service, you compare how demand will change when there is a change in price. This has nothing to do with demand for other goods or services.
So the fact that people are willing to pay more for a UCL final than for an FA Cup 3rd round game vs Salford is completely irrelevant. It would be like declaring that Air Travel is price inelastic because people will pay £400 for a flight to New York, but not for a flight to Dublin.
I haven't resorted to insults, your original statement was indeed "absolute bollocks" and that's not an attack on you personally.