Earlier quoted context omitted.
I thought a major reason was Thatcher letting people who should not be owning a house buy one at a cut price?
No - 'right to buy' is not related to the UK's housing crisis, aside from the fact it depleted social housing stock (which is a separate issue that should not have been allowed to happen). Offering cut-price sales of social property to council tenants is an amazingly powerful tool for giving people ownership over their communities.
It gives people ownership of their houses, not their communities. It's a micro version of the general privatisation problem of selling public assets at a discount for the benefit of private interests; it's just a variant that everyone's allowed a crack at, like the royal mail shares.