You don't need a steady income to invest in bitcoin, there is a difference between having a source of income and having a steady source of income, steady means at a regular interval and there are many bitcoin investor who don't receive funds at such regular intervals, what's needed to invest in bitcoin is a discretionary income which is what's left behind after all you basic bills have been taken care of, you might be recieving money weekly or monthly, your source of income might not be steady at all like how it is for most contractors, just because their income isn't steady doesn't mean they don't have a source of income at all, so please don't misunderstand the two.
Of course, Bitcoin investment does not need a steady source of income. What matters is to have a source of income that will not affect your investment, and you will be able to cover your needs. You can invest even if you are not making a lot of money, as long as you have a way of earning money and you can save from it. I believe that many investors do not have stable income, yet they manage their funds well and only invest what they can afford to hold for a long time.
Furthermore, having a source of income does not mean that someone is balance to invest in Bitcoin. Some people have a job, yet they don’t have anything left after paying for their other needs. Which is why it's important to balance your life first; if you're not financially stable, avoid rushing into Bitcoin. Because some people might end up selling at a loss or at the wrong time. Make sure we don’t joke with our other needs before investing.