Know your cost of living. If you are living in luxury and yet you are only earning a minimal amount of income, hence adjust your lifestyle. If you can do that, you will not find any problem regarding having a single source of income.
How are you going to be leaving a luxury lifestyle when you know you are not financially stable? Then you are just trying to cause problems for yourself, don’t always leave above your standard, if you are trying to impress people, then you are just deceiving yourself, if you don’t have a huge income, then the money that you are supposed to use and invest or start up a business will end up being spent on luxury, and you will be the one to regret it at the end. Some people have just one source of income, and they are fine, they are using the money for the appropriate things that they are supposed to use it for.