I know this sounds dumb, but what do you call people who are rich but they act normal, don't try to show off at all, and is very kind.

Possibly the opposite (antonym) for "snob"?

http://www.powerthesaurus.org/snob/antonyms

Down the earth????

Basically the opposite of having pride

down to earth <~~yes, that works, too.

The term you might be looking for is "down-to-earth" or "humble". These are individuals who possess wealth but don't feel the need to flaunt it or show off. They prefer to lead a modest lifestyle and treat others with kindness and respect. While it is challenging to categorize people solely based on their wealth and behavior, these terms generally describe individuals who are wealthy yet exhibit humility in their actions and interactions with others.