It depends what you want to do. There are plenty of jobs out there you can do without a university degree, and given the cost of a decent university education, if you're smart you might even be financially better off for quite a while if you find a decent job out of school.
There are, however, some fields where a proper academic grounding is very important - engineering is one of those. Plenty of people at my work came to be engineers through non-academic routes, and while there are plenty of tasks they can do just as well as those with a degree (or in some cases better because they have more experience as a result of starting earlier), there are some things that require that broad grounding of academic knowledge that you just won't get on the job.
An example of this: I recently did some work with a supplier who provides video analytics, which run on DSP hardware. The fact that I've studied DSPs at university means I understand the differences in their architecture and how they work, which means I was able to make the right kinds of requests to get the functionality we need in a smart way.
Someone who hadn't been to university doing my job would, of course, be capable of learning about DSPs given time, but it wouldn't be part of their job so they wouldn't know, and they'd ask for functionality that would be difficult and therefore expensive to provide, without realising that what we need could be provided more easily in another way.
The fact is, most jobs you can learn by doing eventually. But that broad grounding gives you the background knowledge you wouldn't pick up just by working, that can be a big help in a lot of fields.