Is it true that crying for matters which relate to this world (loss of job etc.) is makrooh? Therefore should a man hold back his tears if he for example feels like crying in front of his wife? Because I've heard from some people that we should only cry in front of Allah?

Only in Namaz we should not cry for worldly things but other than that there is no such restriction. Yes it depends how valuable thing a person has lost for example if someone has lost his mobile phone and crying in front of people then it’s not worth but imagine if a person has lost his entire property now naturally he will cry. But, it’s better we should not cry for worldly things because may be its an exam and test from Allah (swt) then we should be patient and agree to the Will of Allah (swt) because we don’t know what mysteries are hidden behind that incident.