So first, general knowledge and credibility about Bitcoin are needed, after that, if a person can keep some money aside even with a limited income, then it is possible to start investing in small amounts gradually. It is a step-by-step process, where people start with very small steps, and by keeping it consistent, this wealth starts to grow in the long run.
The size of your income source has never been important for investing and it still is not. You need to make sure you have discretionary money, it doesn't matter how it came from. It may be from your income source, or from alternative income sources or some other way. But it must be discretionary.
If you have discretionary money and have a long-term investment mindset, then you should jump into investing and hold it for the long term through regular (DCA) purchases.
The main problem at present is not having the right idea about Bitcoin before investing, not having the right knowledge, which is part of the basic knowledge. If you still don't know what Bitcoin is and how it works or how profitable Bitcoin can be in long-term investment, then it is natural that you will not be inclined towards Bitcoin. Because you don't have confidence in Bitcoin yet, even if you have discretionary money, you are not yet ready to invest. So firstly, it is important that you have basic knowledge and secondly, it is important that you have a prudent source of income.