If it's popular, even having 2 years of basic experience will be enough to keep you busy. PHP is the poster child for this - it's popular, and people with even

If it's popular, even having 2 years of basic experience will be enough to keep you busy. PHP is the poster child for this - it's popular, and people with even small experience with it can earn a living. I really would caution against trying to be a freelancer who also is an expert-level guru in one tech.