Ticket sales/attendance for games, income from TV, and various other revenue streams are tied to the "marquee names" of an organization.
In the sports world you are rewarded for what you have (done) and not what you (might) do. This explains why no "rookie" would be paid $48 Million. Since Kobe has joined the Lakers they have appeared in 7 finals and won 5 championships.
According to Forbes Magazine the Los Angeles Lakers team value is $1 Billion. They signed a $3.6 Billion television deal with Time Warner Cable along with other deals before the season began with DirecTV, Cox, Verizon, AT&T and Charter for the team's two new regional sports networks, Time Warner Cable Sportsnet and Time Warner Cable Deportes.
No one can convince me that the Laker organization would have gotten that kind of deal without having a superstar player such as Kobe Bryant on the team.
Will he lead the league over the next two years in points, assists, or rebounds? Highly unlikely! Will the Lakers win their 17th championship over the next couple of years? Odds are against them. However they will continue to sell out every home game for as long as Kobe is on the team.
Trust and believe no player has ever earned more money than the owner. The $48 Million the Buss family is paying Kobe is a huge thank you for everything he has done over the years including playing through injuries. He plays to win and he sells lots of tickets.