What is interesting about your question is that what could be two opposite themes are entwined in Walter's character. Walter wants to make something of life beyond being a driver for someone else. He feels repressed as a black man in this white dominated society. Once he learns of the family inheritance from Big Walter, he begs his mother for money to invest in a liquor store. His ambition is to make something for himself and to be his own boss. Unfortunately this ambition is at odds with what his mother wants. She has always dreamed of buying a house in a nice neighborhood. She also wants to pay for Beneatha's college education. There is only enough money for one person's dreams. Walter is selfish in wanting to take his mother's dream away and in the way he guilts her into feeling sorry for him. Walter acts most selfishly when he takes the portion of the money entrusted to him and loses it by giving it to his friend who was going to "pave the way" to getting the liquor licence. This act threatens the family's livelihood and Beneatha's education.
Once that portion of the money is gone, Walter sees the truth of himself for the first time. Be is presented an opportunity to recoup the money by accepting the offer from the racist Mr. Linder, but he finds his pride and turns down the offer. His final ambition is to do what is right for his family, especially his mother, and he makes sure that they move into the house that was his father's legacy.
IN SOME WAY WALTER GO AND TRY TO GET THE MONEY FOR HIS BUSINESS.