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.

How about this? Actually, there are several reasons to believe that artists are paid undeserved, out-of-proportion wages. I hope it helps!