It is correct that Bitcoin is not an investment for those who have no income, but those who do not have income are certainly children and children can never invest in Bitcoin.
The statement that investing in Bitcoin is not good for people without a source of income does not mean the children. There are a lot of people who want to invest in Bitcoin but have yet to do that due to a lack of jobs. Just that investing in bitcoin needs an ongoing effort. If you don't have a stable source of income, you won't be able to invest weekly or monthly, it will be challenging, and you can sell your holdings anytime you need money.
Yeah it would seem more like gambling if one goes beyond discretionary income but some times I do have this feeling if we are only buying bitcoin with an amount can afford to loss them doesn't that make it a gambling because we are afraid we might losses them? lossing can be in many ways but the most fear in this instance is the fear of lossing it to crash or hacks/attacks. I prefer to invest into bitcoin with an amount that I can afford but not the chunks from my discretionary income, if we keep it being only a little of what we can afford to loss to me it's now a gamble which bitcoin is not.
Many individuals believe that gambling is only about risking money without knowing what the outcome will be. However, Bitcoin is safe to invest if you understand it. However, if we are investing a small amount of money because we are afraid of losing everything, it may sound like we do not fully trust the investment. And again being careful does not mean gambling, many people view it as managing risks, and you cannot deceive the market while investing in Bitcoin.