Part 91 operators have a lot of flexibility in their operations not available to commercial flights conducted under Parts 135 or 121. Whenever persons or property is being carried for compensation, different rules apply. One of them involves minimum weather requirements for takeoff under IFR.
The non-commercial Part 91 operator, however, has no such restrictions. We can blast off into any weather conditions we want without needing to meet a visibility minimum or having an alternate airport nearby in case of a problem developing shortly after takeoff. With that flexibility, of course, comes some responsibilities.