Why was Venice so wealthy and powerful?

Answer- Venice became rich and powerful through naval trade, as their geographical position allowed them to be the critical middleman between the Middle East and destinations throughout Europe. (Much like how the Mali Empire in West Africa became extraordinarily wealthy around the same time by controlling the gold trade in that region, even if the actual production mostly happened elsewhere). Northern Italy in the medieval period included some of the largest artisanal manufacturing centers in Europe, which dominated the textile business for centuries (until the early modern rise of English and Dutch manufacturing), as well as producing finely crafted weapons, armor, and other goods. Venice also bordered the Holy Roman Empire, which otherwise had little access to Mediterranean ports after northern Italy had become largely independent of the HRE by the 13th century.

a countries leader should be motivated by the common good of the country.