The right way of thinking is that you can not think of bitcoin as your main income, just a bonus for your salary not to be enough, we should learn more about bitcoin. If you are not sufficiently knowledgeable about the crypto world, it is better to have a regular job.
A lot of people already quit their job because they know that there is much more potential in bitcoin rather than to their regular job and that is the reason why their are treating bitcoin as their main income and i agree to you that they should have more knowledge than the others to become effective in making bitcoin as the source of their income.
Many people thinks of bitcoin as high paying as they can and like it was some kind of life saviour. Its true that by earning bitcoin, people are given chances to have better lives but it can't be done by just relying on bitcoin itself. As a person, you also have to do your part as an earner and a trader.
Bitcoin can be treated as a main source of income that is why there are people who left their jobs for bitcoin but in my own opinion, it would still be better to have a regular job. Bitcoin prices and all other cryptos are easily affected by bad news and, demand and supply that anytime it can dumped making that high profit turns into loss.
indeed the profit earned from bitcoin sometimes exceeds our basic salary but bitcoin can not be our main income. because if you put all your live load on bitcoin this will be very risky in your old age. it would be better bitcoin used as a side job for doing bitcoin you can anytime and anywhere. this way you will not worry about your old age because you already have pension in your old age from where you work.