Simply, it means, 특별히 더 행복하지 않다.
"특별히 더 행복해보이지 않는 것만보더라도",
Here, "....만 보더라도" = 다른것(증거)도 있는데 이것만으로도.
We do have more other evidences,
but only from this fact(굴지의 기업총수인데 특별히 더 행복해보이지 않는것).. bla-bla-bla
He doesn't looks more happier than somebody else because he is (xxxxx),
From this fact, we can understood (realized) that (xxxx something truth? )
A verbose representation....