We don't have infrastructure because the last 15 years of defunding and poverty in this country destroyed it.
Workers coming in contribute to the country's wealth. They contribute to the Treasury in their taxes - but only if they are given the legal jobs they come here looking for. Keep them locked in a hotel on £30 a week, and yes they cost money. Put them on the building sites, supermarkets, factories, distribution centres they came here to work in and they will immediately net contributors.
They are young and keen and don't actually need much infrastructure. They don't need the NHS as much as the older, preexisting population needs by a long shot. Most of them are men, as you say, so they're not adding pressure to maternity wards.
The birth rate is falling, so we have plenty of room in our schools for those who bring their partners and have families here.
Many are happy with shared housing, because they aren't here for the long term - they want to earn a bunch of money and take it home to buy a house - exactly like my own family members did here in the 1960's, in fact! They're also quite literally often BUILDING housing when they're here, so again - net contributors!
I'm an immigrant and we came here 20 years ago with money from my own country 20 years ago and we bought a house, and are very much net contributors. Is that okay because we're white though?
So can you please specify exactly what part of the infrastructure will collapse because a bunch of ambitious, healthy young men are coming here to take jobs that are readily available to them?