It is realistic and contractors could earn a good rate in a good market. But contractors are the ones to get laid off first in a tough market. My company has already started laying off the contractors.
Does he earn that or bill that? There's a difference after the consulting company takes their cut. Or the expenses Campbell mentioned. Also consultants have to pay for their own health insurance which is expensive. Similarly, the actual pay depends on the number of hours he works each year.
Pay varies by city. If he lives in a city that is expensive to live in (New York, San Francisco, etc), rates are going to be higher than they are in more rural areas.