[Chris2048]

> By buying a house someone else could have bought

I interpret "others are struggling having roof over their heads" as struggling to make rent, not purchase a house. If you struggle to pay the bills, it might be hard to get a mortgage.

> thus increasing the prices for everyone

The price is higher because someone else is taking on the risk. The alternative is prices are lower, but increasing the risk (and up-front cashflow requirements) for everyone.

> How does buying and renting a house provide something not already there

The house was already there to buy. Now it's there to rent. Again, I'd assume those who struggle the most are looking for rentals.