It was never a very sensible scheme to start with:
The government's Help to Buy scheme is facing the axe amid concerns it is helping wealthier households and pushing up house prices.
The Telegraph understands that ministers are planning a “fundamental review” of the policy that could see it replaced with a scheme that is "more targeted on those it is meant to be helping."
Subsidising the purchase of something you've already decided is too expensive is not the way to do it. For you're just adding more money to the flow chasing that already too expensive thing.
And yet it was done - why? Because political pressure to do something and logic to do the right thing aren't - as we can note - the same thing. House prices were/are such that people find it very difficult to get on the ladder. Reducing the price to be paid would help but that might mean confronting one or other shibboleth. Like allowing people to build houses people want to live in where they'd like to live instead of where the planners damn well tell them to.
Thus we get policy which not just doesn't quite address the justificatory problem given but is entirely counter-productive.
The point being that politics isn't a good way to be managing things. For what bubbles to the top of that political do something list, what politics suggests, or allows to, be done, tends not to be what either needs or should be done. Better instead to use politics to decide that absolute minimum of things which can only be dealt with in that manner and leave the rest of life to us the people to deal with in a very much less inefficient manner.