Economic situation of a country is a fairly complex picture that cannot be measured by a single scalar value. GDP per capita is not useless, but just one value among many. Same as you wouldn't try to measure an individual's overall health by their BMI alone. It tells you
something, especially on the extreme ends of the distribution, but in the middle, not that much.
Yeah, OECD is very political. No disagreement about that.
But I would say that the correlation of "being attractive for FDI" and "having good standards of living among the general population" is rather high and given that FDI tends to predate said growth of standards of living, there actually may be causality.
Excluding resource-rich countries that grew fat on something that comes out of the earth, pretty much every country whose standards of living soared since, say, 1950, attracted a lot of FDI beforehand.
After all, the same things that attract investors (stability, low crime, high educational attainment, reliable electricity supply, rule of law) tend to be good for the citizens as well.