The most appropriate answer to this question is that “it is up to your skills and your personal willing”. If you have dedicated yourself towards working 40 hours per week then obviously you will be earning more as compared to the one who is working 20 hours in a week. But I personally feel that if you are really a highly skilled person then you can earn pretty much by working for few hours only. In fact, you can take your income skyrocket if you tend to give more than enough time and your skills are more than enough.
It is a say that “it is not difficult to achieve a goal but it is difficult to make up your mind up to achieve that goal”. If you have decided to earn a full-time salary from freelance work then, believe me, you will find a way to do that. Let me give you an example of myself as I am earning my full time earning of 6,000 dollars per month by working 40 hours per week as a graphic designer. If I compare my skills to that earning then I am earning quite well. I am not all in all in graphic designing but have an experience of 2 years.
If you attach hot certifications to your resume then you will be having fair chance to come across a good deal. Upwork skill test answers are available to clear the certification test in top positions. Ultimately that deal might give you a great income and solid credibility. In other words, your budget should be according to your skills while sending any proposals. It would be a bad idea if you charge 30 dollars per hour in very early days of your career.
You can earn on upwork even if you don’t have hot skills like programming but do have a strong hold on English and managerial activities. I know some professional writers who are earning in thousands against their couple of articles per month. It is their highly professional writing skills that are giving them huge relief in terms of earning.
You can earn well as being an individual freelancer. The first aspect is your motivation and dedication. If you are really a motivated professional and know how to keep professional and personal life separate then consider half of the work done. If you specifically give time to your freelancing work without getting involved in Facebook activities or any other then you will be able to accomplish your tasks on time. Plus, you need to make sure that you are always reachable by giving every possible contact details to your employers.
You can manage to set up your own agency where you can recruit professionals from every possible field and then get freelance projects from upwork. Again it mainly depends on the skills of your agency employees. If they have the capabilities of doing something great then your income can go higher and higher within days.
The conclusion is that skills are the basic parts of your income but your motivation comes first. You can earn very well even if you follow disciplined steps no matter where you are standing in terms of experience and knowledge.