Again, I'm very aware of the reality of how it all actually played out. It's history, it happened. And, I'm not trying to take anything away from Roy or their relationship. He did what he felt he had to do to keep things financially in order with all of Walt's "flights of fancy", if you will.
I remember reading about one particular happening regarding the release of Snow White and the Seven Dwarfs. There was a screening of the final cut of the film at the studio. Walt was displeased with the prince in the last scene. He "shimmied". Something had gone awry during the filming of those animation frames. Walt wanted to fix the problem, Roy was, of course, concerned about costs. Walt said he would get back to him on that. When Walt came back to Roy with the answer of $50,000, Roy, purportedly, said "Let the prince shimmy." Walt acquiesced.
The original budget for the film had been estimated at 500K, but, eventually ballooned to about 1.5M. Fortunately, it made about 4M (if I remember correctly) in it's original release, "shimmying" prince, and all.
As far as the land purchases in Florida go, I thought I remember reading that it was a business relationship of Walt's (possibly, a developer?), that he had also consulted with during the development of DL, that suggested buying the land in Florida under assumed company names.? Again, I'm not speaking to Roy's involvement otherwise in all of that, just that if word had gotten out before it did, the land prices in that area would have skyrocketed sooner than they did, and they probably would have acquired a lot less of it.
Anyway, I'm sure we could discuss it all for hours.
The main point where you and I disagree is whether or not it would have all happened without Roy. I believe it would have. Not exactly the way it did, but still would have.
Walt was a driven visionary, able to inspire, persuade, and surround himself with people that could do things he couldn't, but, he wanted to still get done. I still believe he would have found ways to surround himself with others that had the financial skills to get done what he wanted, but, also to rein him in, etc. Granted, not a trusted brother relationship, but, I still believe he would have found someone/people.
What it all boils down to is, we'll never really know, because that's not the way it played out.
I, honestly, believe he would have gotten their with or without Roy.