Students prostitution (to pay for tuition, rent and the likes) is common in various countries. It's even legal in a lot of countries, like the UK (do a search for "sugar daddies website" and there you have it).
In Japan, it's been taken a bit further openly, as even highschoolers do it. Ie, minors. Usually to buy themselves clothes, electronics, games, etc... There're apps on mobile phone, or websites, to allow people to meet. Sex is not necessarily included, but eventually negotiated.
Hideaki Anno (of Evangelion fame) even made a movie about it (https://en.wikipedia.org/wiki/Love_%26_Pop). It pictures the danger and creepiness of such activity. Enjou Kosai is indeed dangerous and can, of course, lead to prostitution, drug, STDs and death. But teens are teens, they don't necessarily grasp the consequences of their actions.
It's a societal problem in every country, especially consumer societies, where there's a value gap between those who have and those who don't. After all, it's easy money. Just count the stains on the ceiling and get the cash.
It's not going to be fixed with laws, police or moralizing words.