It doesn't matter about the average person if it only takes one successful objection to stop a project.

I think you misread it. The context was, _not low_ (ie. high) for the average person. For someone with a higher than average wealth however, £5k isn't all that much, especially if it could potentially protect the value of their assets

I was referring to the "not that expensive".

Maybe I misread it then. I interpreted it as "not low for the average person, but not that expensive _for someone with greater than average wealth_"

Yes, that's how I intended it.