Society has some seriously whacked values. We are not willing to pay much for the teachers who are responsible for educating our society. We are willing to let banks and bankers take money from us for holding our money. We are willing to pay outrageous sums for "entertainment". But as others have said, that is capitalism.
The real problems come in the form of exploitation. NFL players have a union and have made sure they get a portion of the pie. T&F athletes have no such leverage. The apparel companies and federations (USATF) are in complete control of the revenue stream and the athletes are promised nothing of that. Just as the NCAA has exploited college football and basketball players, T&F is exploiting its athletes. The product is the athletes, but the athletes are not paid for their performances.
Imagine how well a bar would do if they were known for live music and told the bands they could put out a hat on the front of the stage, but they had to pay for their food, drinks, and electricity usage. How many bands would play there. T&F pretty much operates this way, but people are willing to run for nothing and even pay entry fees so someone else gets the cover charge.
True there is not as big a money stream as other sports, but other sports pay their athletes a portion.