> by 2035, the wealth of the richest 200 families will be larger than the whole UK GDP

Those things are measured in different units, which automatically throws doubt on the ability of the source to be statistically rigorous in any other way.

One is measured in pounds. The other is measured in pounds. Seems pretty comparable.

If you're being deliberately stupid you could pretend it's a comparison between pounds and pounds per year, but everyone who is at least minimally literate in the subject understands that "GDP" here means "the amount of value produced in a year".