@Zaane YANBU at ALL !!!
IMO, if a home is sold to someone with 35% off - and in some cases it's 50 or 60%, the council should put it into building new affordable homes (to RENT!) Then if that person puts the house on the market within ten years, whatever profit they make, they should give 50% back to the council.
Eg, if they bought their house on the right-to-buy for £50K, (and it was valued at £100K,) and they sold it after 3 or 4 years for £120,000, they should give half of the £70K profit back to the council.
It is annoying, but even MORE annoying is this that happened some ten years ago.
A woman I know (and her DH,) lived in a council house from 2000 to 2009, and bought it on the 'right to buy' for £60K (it was valued at £120K.) They got 50% off!
They continued living there for 4-5 years til 2014 ish, then sold it for £140K, making £80K on it! They then moved into a little private let 2-bed house.
They squandered most of the money on new cars, holidays, clothes, expensive tech, a caravan (which got stolen and was not insured, so there was £6K gone,) then another caravan, and all sorts of shit. They had £10K left within 2 years.
In 2015 they went on the housing list, and claimed overcrowding as the son and daughter (now teens) were sharing a bedroom. In 2017, they we allocated a 3 bed semi detached house from a housing association.
So they made £80K on their right to buy, sold it, went into private let, squandered all the money, then went back into fucking social housing again. I am SURE there has to be a law against this.
Another couple I used to know, were 'homeowner/mortgage owners' for 20 years. They got £70K into debt by living above their means, renovating/redecorating the house, going on 2 or 3 holidays abroad per year, buying multiple tech items by Apple, having a brand new car each every year, amongst many other things...
In 2016 they went bankrupt, wrote off all the debt, surrendered their house/had their house repossessed, and moved into private let. They ALSO went on the housing list.
In 2018, they got offered a snug little 2 bed semi-detached bungalow owned by a housing association, that cost £65 a week rent. No debt and a cosy little social housing bungalow with a tenancy for life.
So, so, SO fucking annoying! 
As I say, I have no massive issue with people buying their council house, but the council MUST put the money into building new affordable homes to rent, and the person buying their council home, must give 50% of any profit they make, if they sell the house within ten years.
Why the fuck should they be able to buy a £140K house for £70K, and then sell it, and run off with all that profit a couple of years later? And even worse, get social housing again within 2 to 4 years of making a killing on their right to buy?!!