Question: It's never explained why Bobby would ever even consider going into business with Jeff? It's not as if Jeff is some great business mind. The entire Dearly family has no respect for him and treat him like a buffoon. There's absolutely no reason given for why Bobby would ever set foot on their property, much less inside their house.
Answer: I doubt anyone can give THE answer with any degree of certainty. This may be why your question hasn't been anwered yet. One possible answer lies in the film's setting, Verplanck, NY. In real life, Verplanck is a small area (less than ONE square mile) with maybe 300 houses within the city of Cortlandt. Such an area, where "everyone knows everyone else," is classified as a hamlet (smaller than a village). Household/ family income probably falls below the U.S. median. In the movie, residents were portrayed as poor and not very intelligent (read: dimwitted, "Forest Gump smart" or "idiots"). Jeph and Bobby were part of this close-knit community and probably had more similarities than differences. Bobby didn't even have money to start the business - his brother Murph put up his half. Who would become business partners with someone who didn't have the start-up money? Someone in the hamlet who needed a job and could get money from his parents - Jeph. [Why would Jeph partner with Bobby?].
Answer: [Continued] Bobby may have had a better "presentation of self" than Jeph and LOOKED smarter, but he had his own deficiencies (plus mowed over Peaches, losing that contract, and intended to kill Jeph, not Mona). Would a stranger (outsider) be willing to enter a business agreement with Bobby? When choosing someone you have known for years, you have a good idea of what to expect from that person and might have fewer doubts and face fewer unknowns (such as whether the person can be trusted). Partnering with a stranger can be a very risky endeavor. When starting a business, there's no guarantee that you will be successful. Landscaping businesses/ jobs involve hard physical labor - something a lot of people are not interested in doing, so Bobby may not have had (m) any potential candidates with the exception of Jeph.
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