I have several friends without university degrees that are software devs. The difficulty seems really variable. If you get that first job and can stay there for a couple of years, I would say it is often easier than going to University. Personally, I didn't consider comp sci to be a particularly difficult degree (in comparison to physics or pure math for example), but exams and assignments are definitely more stressful than what you normally run into in a job.

There is a lot of risk with going without a degree, though. Take the example of the person who posted a few days ago about working as an intern for 8 months, getting into a fight with his boss over money and finding himself without a job. I'll take the stress of an exam over that any day. Trying to find a junior position without an academic background often means putting yourself at the mercy of unscrupulous people :-(

I got a free ride through school, but I went through in the 80's when it was also comparatively cheap. At that time, I don't think there was much of a downside to getting a degree. If I were to do it again (on my own dime), though, I would seriously think about trying to get an apprenticeship at 18 instead. If you can work for those 4 years, I think you would be considerably ahead financially.