This would have easily been prevented by basic due diligence from the investors. Possibly that is why the courts ruled against them.
It is possible that they saw the 4 floors as "representative" of all the floors that would be built, and just expected that there would be 40.
Wichita Falls is pretty much on the Texas/Oklahoma border and that area was filled with oil money at that time. Only 10 years later, Tulsa Oklahoma was building 40+ floor skyscrapers. But prior to that, skyscrapers seemed to be limited to NYC, Philadelphia and Chicago.
40 (forty) floors say
I understand people can be lazy and make mistakes, but that's pretty egregious.
A comparison for today might be to put the plans for a computer chip in front of an average non-technical small-time investor and then use slippery language to trick them into believing it is something it's not. Tell them it will be the next big thing and will return their money tenfold, and greed does the rest.
It's quite possible back then that the investors, having never seen a skyscraper - or maybe even a proper blueprint - just didn't know what they were looking at, never mind doing any kind of real due diligence.
The scam is that windmills don't actually scale very well. If you have 100 MW blowing at the blades, you need a tower that can handle 100 MW of force - or something like that.
Of course, what do I know? I am but a humble computer nerd.