an idealist
Examples
An idealist is a person who helps other people to be prosperous.
An idealist is one who, on noticing that roses smell better than a cabbage, concludes that it will also make better soup.
I'm an idealist without illusions.
An idealist believes the short run doesn't count. A cynic believes the long run doesn't matter. A realist believes that what is done or left undone in the short run determines the long run.
I am an idealist. I don't know where I'm going but I'm on my way.
The opposite of an idealist is too often a man without love.