Using your sentence as a basis, I would wordsmith it as:
There are several reasons to believe that artists are paid unnecessarily high *wages* that they don't *actually* deserve.
- Wages isn't the word we tend to use in this case. A wage would imply something recurring (like a weekly payment), but usually, artists are paid for a project, so the more appropriate word here is "salary" or "artists receive/are given unnecessarily high/large compensation".
-You could also use the word "merit" to indicate something "deserved with effort."
Ex: There are several reasons to believe that artists are paid disproportionately high salaries that are not merited.