Hmm... I don't know how sadist is used in English, but in German, there's still a difference between the two words. Schadenfreude is used more general or in a social context, for example if you feel happy when your overly rich and arrogant neighbours Porsche broke. Sadism on the other hand is used for physical pain and almost exclusively in sexual context.
I've never heard the word Luftmensch. Träumer would be the word for the description, meaning dreamer. And Torschlusspanik while correct often means not only the general fear of diminishing opportunities but most often the fear of a aging person of not finding a partner.
(Copypaste, I know)
(Im german too.)