Actually, a steady income is a MUST for saving a part of your salary in Bitcoin, especially if you employ a DCA sort of strategy. Because it doesn't matter what you call "prepared", if you don't have a steady income then you definitely ARE NOT ready.
U are right , before going into Bitcoin investment it is important one have a source of income , I have recognized the importance of steady income with my own investment journey , it is also good for long term investment success, when their is a stable financial income either with your job or other investment you can manage risk and it enable one be consistent in their investment.
It has been over emphasized on by JJG and some members here that having a stable source of income is good, someone without a stable source of income is just like someone going to the farm without hoe or cutlass because you will definitely work nothing and then again it is not just about having a stable source of income, it is about determination, perseverance ( don't shake or move when market is going in the opposite direction because you are not a trader because definitely the market will retrace ) and know the reason why you want to hold for a long term because this is what will motivate an investor the more to keep accumulating and holding even when they want to give up.