You have to make sure that your financial situation allows you to say I quit without later regretting it.
1. Keep in mind, if you quit, most likely you will NOT be able to claim unemployment benefits.
2. Dig real deep inside of you ask yourself what's really going on.
3. Is the issue task, money, company culture related or a combo of all?
It's not an easy step to take, but on the other hand if you feel abused, if you feel you've done everything positively to change the scope of your situation and you are financially stable and can afford it without affecting you and your family's life, then by all means seize the moment and go for it.
Weigh out all the pros and cons.
Also, brush up the good old resume and put yourself out there before quitting. Sometimes just putting yourself out there helps you distract yourself from making a decision you may not be happy with later.
Think it through, consult with loved one's and follow your passions.
Thank you for the question.