Yes, Nedry owned his IT company, but Hammond was withholding Nedry's final paycheck until debugging was done. Which had already gone over budget due to feature creep, so Nedry was doing it himself because he didn't have money to pay his people because Hammond wouldn't give him the money they agreed on. Hence why Nedry was looking to make some side money, he's literally doing all that debugging and final system fixes for free on the promise that he won't be screwed again by Hammond. IIRC anyway, its been like 30 years since I read the book... And a lot of my perspective changed as I got older and I got more experience in the industry. As a kid, I thought you took the job you should do the job, but as an adult I understand a lot better the dynamics of the situation and while I still think if you took the job you should do the job, I completely understand the feeling of getting Fucked by someone who would rather throw money at lawyers than just pay what they agreed on.

I have been in his position, and while I didn't betray the client and get killed, I really understand his mindset and "Fuck-it" attitude. Hammond is wealthy and using his position and power to spare as much expense as possible and step on as many contractors as possible. Kind of like an Orange Cheeto I know of. I had a company I work for that had to file bankruptcy because a half-billion dollar a year company hired us then charged back their initial payment and refused to issue final payment unless we did a ton of extra work, and when we did that, they just said "thanks" and vanished. Apparently American Express lets you contest a payment 6-12 months after it was issued and their stance is if you want your money you should sue.