What doesn't click for people though not looking at this head on is how detrimental $4k per month is. For example, I had a very high starting salary for a new grad ($86k) my total monthly check minus health insurance and taxes was $4400... my loan payment for a 10 year repayment... $4100. It isn't feasible. Unless you can find living, food, gas, car insurance, clothing, etc for $300/month.
So then I am sure the next thought is "ok, I will pay it off over 25 years"... sure, fine, fine. Your payment decreases to $2700/month. So now you have $1700/month for any other debts, rent/mortgage, gas, car insurance, food, clothes, etc. It might be feasible, but it would be very, very tight. Very tight. So now you are living like a student for 25 years post-graduation.
Now I know you mentioned income based repayment at the end... I am currently paying ~$270ish/month off what was half a years worth of work (based on taxes and I submit that info each November). So in November, my payment will go up because I will have made a full year salary at that point. It should double, so maybe not quite $600, but close to.