It's not only price but publicity. But price is an issue. If there are 6,000 people paying just £1 that's £6,000 lost so clearly £10 is £60,000 - that won't be covered by the prize money. So let's say £15 admission which would mean 4000 extra people needed to break even.
Do you think that is achievable?
I realise this is fagpacket maths but the general point would still stand even with more accurate calculations.