Because, overall the wind power is the cheapest energy source available, and has been for a decade (recently overtaken by solar in some markets).

Something that is cheap can have some percent wasted and still be cheaper overall than more expensive options.

Focussing only on the waste without that bigger context is at best a false economy, at worst fossil fuel promoting propaganda.

What good is cheap if you can’t use it?

Why would I want to pay for cheap wind energy I can’t use, and also pay for gas energy that I can use? Unless the cost of the wind is £0, paying for wind in addition to gas is just a waste of money.

The wind is 94% used. Which reduces the gas use. What do you mean "can't use"?

you should see how much per MW/h it costs for power from a "Peaker" power plant.

Looks like $150-$198/MWh

https://en.wikipedia.org/wiki/Peaking_power_plant

In a sense: because all it does is move money from one place to another.

That's very different to wasting money in a way that actually uses up physical resources or people's time.