It's true that if you fail to plan, then you've planned to fail, therefore it's very important to plan for old age, because old age must come, unless the person unfortunately dies young, in old age you won't have the strength to work and earn money to take care of your responsibilities, without help from loved ones, the person will live a miserable life. So it's very important to have budget for your income, and try to save and have an investment, no matter how small, so you can fall back on them when you're old.
Although many people especially in underdeveloped countries where poverty is much, they don't even make enough money to feed their families, not to talk about having savings or investments, they're so impoverished that they only struggle for food to eat. In their own cases, you can't really blame them for not saving or investing for their futures, because even when they have the mindset to invest, their poverty will not let them to actualize it.
In my opinion, failure occurs because the planning we do cannot work well and no one plans failure for themselves and I agree with what you say. It is very important for us to be able to have plans for the future because we will never know when we will will not be able to do work that can provide us with income by having a plan for the future so when the time comes when we are no longer able to do work, we can enjoy the results of what we have prepared while still able to work.
For those who can only earn enough to eat, of course it will be impossible for them to think about their future so this will continue until they earn enough income for their needs and some of it they can save, but this will it is very difficult if the country where they live does not make it easy for their people to generate a decent income for them.