The major cause of both positives and negatives in sports today is the huge amount of TV money and exposure that athletes and their sports get.
The money and the exposure make it possible for everyone involved with the more popular sports to make huge amounts of money. All you have to do is look at the kinds of salaries that athletes get and the prices that franchises sell for.
The major negatives have to do with the arrogance and sense of entitlement that we see in both players and owners. You have owners demanding new stadiums that are paid for by taxpayers. You have players acting in incredibly arrogant ways, doing things like attacking cashiers at pancake houses (one of the Lakers just did this).
So, the money in pro sports today are the main cause of the positives and negatives of the business.