Adam Clarke on Luke 19:2

Zaccheus - It is not unlikely that this person was a Jew by birth, see Luk 19:9; but because he had engaged in a business so infamous, in the eyes of the Jews, he was considered as a mere heathen, Luk 19:7.

Chief among the publicans - Either a farmer-general of the taxes, who had subordinate collectors under him: or else the most respectable and honorable man among that class at Jericho.

He was rich - And therefore the more unlikely to pay attention to an impoverished Messiah, preaching a doctrine of universal mortification and self-denial.