I think you should ask this question to some professors in computer science or engineering.  As far as I know it is not just the salary the professors get, but they also get (if you try hard) funding from different industries/companies for several research.  You can pay yourself, under the watchful eyes of donors, dept head, and graduate school, from those research funds.  You will be trickling few dollars, so called research assistanceship,  to your grad students to help you on your research projects (and they get MS/Phd from you for that!), but you will be paying yourself good amount of money from the research fund.  If you get $100k as salary, quite possibly you can get another big amount from your research fund.  Not to mention, you can work as "consultant" to the industry in your spare time.   Again, this is just my thought.  You can verify this with professors!  I have seen several talented engineering students with MS degree employed in industry just to come back to school few years later for a PhD and then ended up being professors in universities.  So there must be reason why these smart people preferred academic area when they were already doing great in industry!