You've put your finger on precisely why, in my experience, more people don't save. They know they don't know what's coming in the future. They know what their money will buy now. Thus they conclude they'd rather go with a sure thing, and let the future take care of itself.
I happen to the very model of the modern major...savings nut. But I cannot honestly say to anyone that giving up so many opportunities to consume things, places, and experiences now, when I'm young and strong, is worth it so that I can hopefully pay for mere subsistence later as an old person outliving any reasonable term of life, and then undergoing a cashectomy in my 90s by various corporations. I completely understand why people spend it all now, and go into debt for more. I don't do that, but I understand it.
In our society, the future is for corporations; we all die in one generation, they go on, the Undead. We are their serfs. And even if I have the money in the future for all the things I'm depriving myself of now to save, I will be older, more fragile, more brittle in my personhood as older people tend to be. Not to mention that "retirement" no longer means stopping working early enough to have a life; now it means working till you still drop, then having enough money to pay for expensive life-extension technology.
Finally, you put your finger on another reason many people abhor financial planning: there is no certainty of outcomes whatever. Just like a casino. Plus who isn't cynical these days, having watched CxOs raid pensions left and right and get away with it? These financial planning books are always ridiculously--sometimes insultingly--simplistic. I found this one that way. Often financial planning books are tract about how to play a game, the game of planning, the game of investing. If one enjoys doing that for its own sake, then great. But let's not mistake it for anything certain, beneficial, or reliable. And that's the sad part, that people can work hard all their lives, live the best they can, do their jobs and their duty...and still get royally shafted!