It’s not advisable to have a single source of income. It may be possible to live and cope fine with a single source of income but with the rate of inflation, your single income would start to be looking small for and wouldn’t be enogh anymore to keep up with living expenses.
How much you earn would be a good determinant on your lifestyle and even if you earn a whole lot of money, it would start to tell on your pockets later on with the rate of inflation and inflation with the prices of goods and services skyrocketing, it’s advisable to have a second means where income incomes in.
but if the source of income is large and sufficient, even more than enough to meet needs and so on, then there is no problem. but it's not good either, if you really have a large income you have to be able to take advantage of it, such as saving to open another business so that you have other income apart from your main job. It's true what you said, maybe as time goes by everything will add up. Of course we have to be able to adapt to technological advances too, but don't forget that with increasing income, the possibility of lifestyle can also increase.
It's good that we can have more than just one income, if we are still able to do it then there's nothing wrong with that because that's a good thing too. Also, having other income ensures that when the main income is in trouble, there is still other income that can be relied on to help in terms of funding, but of course we also have to pay attention to ourselves, whether we can afford it or not by having more than one income. because of course having more than one income will probably take energy too.
Yes, of course it is true that if one source of income is managed well, there will be no significant problems. When carrying out a job, of course we are not required to be greedy, but how shrewd we are in managing finances according to income and needs. If someone has a business spirit then he will not feel that just one job is enough but he will look at other opportunities to increase his income. Maybe it's different from other people who have the spirit of an employee, it might be a little difficult to develop themselves to increase their income outside of their binding work.