They dont live in mediocre conditions..trust me. They may have to live with a few more to make it affordable but its never bad. They spend very little time at home, probably more time in the gym..lol.
Most teams make arrangements for their players on housing. For example they have furnished apts and have lower rents than you and I would. You will also find that college guys will live together, and since they have already done that for 3-4 years its all good.
The big problem is not in season but off season. College guys tend to find decent part time jobs or give lessons to make money. College guys have wives that work and can help support. Yes I admit having a wife with kids is pretty hard to support on milb salary , but that isnt about our kids, so dont worry about it. If they are meant to make a ml team they will make it work.
Thats why you go to college first unless someone is going to give your HS player a lot of money.
While a raise could be needed , paying someone 15k for 5 months (3000 a month) with no education is more than college grads might earn.
JMO