what is to be considered is that those that get to their retirement age are older people who have sacrificed almost all of their lives working for a company, an organization, or the government. which a person in that age is supposed to go and have an effective rest of their life because their life is almost going to end, so even though they have the money that they have already saved, they deserve to have effective care from their children and their grandchildren because, at their age of retirement, they need to rest and be cared for because of their old age.
Someone needs to get a means of earning money regardless of their age. Even after your retirement, business is still very important. Those who retire have children and grandchildren, so even if they establish a business, it is still okay. Although they may have money after their retirement, any money in your account as long as you touch it will still be gone, and you will go broke. So why not use this opportunity to not get anything to do and make yourself busy with your personal business?
If someone is retired, they need to get a business in case of any family emergency that will need money and other things. You know that if you save money and don’t work anymore, you will still go back to your savings, so it is better if you create a business before you touch your saved money; if not, it will finish and you will go broke again.
So I don't think it is advised for them to work again or have a business because it will add up more stress than reduce it.
It is advisable to get businesses after retirement, However stress ever finished if you on this earth, the best thing is to limit yourself from the kind of things you do, and know the kind of business you create since you are old enough. But for you to stay at home eating your saved money, without getting another source of income just know that the money will later finish and you will go back to where you were coming from.