"Isn't that high" is not with reference to the median, but with reference to their pre-existing career prospects.
The salary of MPs is not sufficient, by a long way, to attract almost any one from other competing careers.
(I don’t have a solution, every option I’ve heard comes with downsides)
The median UK salary is around £30,000.
MPs who become part of the government often do fairly well out of it, obviously more so the more senior the government position(s) they hold, and there are a lot more members of the government than most people realise. But rank and file MPs often get a pretty raw deal compared to the kinds of alternative options anyone with the attributes to be a good MP would probably have.
https://5050parliament.co.uk/get-elected/
Maybe we'd be better off if MPs had to study and practise as much as an NHS consultant has to before they can run the country?