independently making money has always been allowed, kind of. That depends on the degree of this independence.
Yes, if you have a totally independent business that with earnings that has nothing to do with the NCAA sport you are participating in then sure no problem. The problem is typically this is not practical.
Taking your example of a Hollywood actress attends college and play an NCAA sport, can she keep the money from the actress side? Yes as long as that side is totally independent from her sport. So a child actor say Shirley Temple grows up and happens to be a talented athlete to play in NCAA volley then yes she can collect money for her acting job and not violate NCAA rules. Now if the order is reversed, say a very talented basketball player Michael Jordan while still at North Carolina was approached by Hollywood to do a Bugs Bunny movie over the summer, that would be a violation because the opportunity would not be possible without his fame as a basketball player first, the whatever money offered is somewhat tied to his athletic participation at the school, so the movie is using in some way shape form his name, image or likeness. That would have been a violation.
So if someone can prove there is no relation between the NCAA sport and the activity he/she is getting paid for, no problem. Most of the time there is some relation it's just a matter of degree.
Technically you can have a college basketball player participating in NCAA games, while playing professional baseball and getting paid, as long as the basketball didn't lead to the baseball.
There was a case in 2013, an NCAA wrestler from Minnesota created a youtube video, a music video. In the video he identified himself as an athlete and a wrestler, and that was enough for NCAA to declare him ineligible due to his receiving compensation for that video. If he had not mentioned the name of his school, or that he is a wrestler, or wear a shirt with the school's name on it etc...yes he could have gotten away with it. Later on he said he did this on purpose to see if NCAA would act, and by NCAA acting this thing got noticed and his video hits skyrocketed.
The NIL took away this restriction.