and a lot of people don't have access to the kind of networks that could help them fulfil their potential.
It's kind of like how no one chooses to be obese. Choosing to eat the right food and exercise regularly obviously helps, but there are a lot of other factors - genetics, gut bacteria - that people have no control over, and a lot of other competing factors and habits - the way your parents brought you up, the amount of free time you have to shop and cook, access to healthy food, actual interest in cooking - that make these choices harder than they are in a vacuum.
The other thing I'd add is that people who have to take jobs like this don't have a lot of negotiating power in the labour market, which means they can easily be screwed over by their employer. It's these people who should be getting the benefits of safety nets and unions to support their quality of life - but the strongest safety nets and unions are for professions that don't need as much protection.