What you’ve said is very true, but my belief is that they’ve spent £70m, which is no insignificant sum, so somebody within the project must clearly still think it’s viable to press ahead and has a fighting chance of happening. Whoever is funding this must do all kinds of viability studies to see whether investing into the project will actually amount to anything and be worth their while investing in, because no financier would want to waste £70m and 9 years of their time on a project that’s going nowhere.
Also, other projects with a similarly chequered and long history have pulled through in the past. Look at HS2, for instance (admittedly not a theme park); announced in 2003, didn’t get the confirmed go-ahead until 2020, and phase 1 isn’t opening until 2029. Or the American Dream entertainment complex in New Jersey; that was in planning from the 80s or 90s, but didn’t open until 2019 and had many similar bumps in the road along the way. I believe many of the recently opened projects in Dubai had also been in planning for years and years (at least since the mid-2000s, easily) and had a similarly bumpy road to opening.
My point is; no benefactor would invest into this if they didn’t think they could bring it to life, because investing £70m and 9 years into a project that’s known to be going nowhere is surely about as useful to them as throwing £70m into a river. Someone is clearly investing substantial amounts of money into it for it to have gotten as far as it has (£70m doesn’t grow on trees), and the company themselves have said that they have an investor. And no investor would get into a project without having done viability studies; they will likely have done some algorithm or something to calculate their potential profit margins and whether the project has a chance of happening.
That’s just my take on it, though; I can sense few will agree, so in hindsight, I apologise for wasting all of your time with my opinion.