That's the crux of this whole gig economy debate - for some people, these kinds of jobs are ideal: zero hours contracts, with the ability to work more or less depending on what else is going on in your life.
That being said, some people take these jobs because they're the only ones they can get. I don't know your circumstances, so I'm going to guess here, but from what you write it sounds like you have the safety net of your parents if things go wrong. While you study you may also have access to a student loan and/or support from your parents mandated by law (let's not get into an argument about how crappy student loans are, but at least they're an income during your studies). Since you're attending university, I might guess you're at an age where you don't yet care about paying into a pension. Again - making wild assumptions here - but if you don't have kids, you probably don't care if your work-life balance is skewed heavily towards studying and earning, at the expense of sleep and general health.
For some others, though, their job is all they have, and "gig economy" jobs are the only ones they can get. This creates the perfect environment for exploitative working practices, where dodgy loopholes are used to underpay and overwork staff, who can be dropped at an instant if the company needs to save money or if workers start to complain about conditions.
If Deliveroo and other gigs were worked by students in their free time, I don't think this would be such an issue. The problem is that, increasingly, people without safety nets are joining these companies and working effectively full time, and no longer just for occasional "gigs" a few times a week. That, in my book, requires that they are given the same rights as any other full time workers: holidays, sick pay, pension contributions, grievance procedures and other benefits.