Athletes do not get taxed on "half their income." Each bracket of income is taxed at a progressively higher rate, so the first $10k for everyone is taxed at the same 10% rate. The next $30k for everyone is taxed at the same 12% rate. The next $45k for everyone is taxed at the same 22% rate, etc. The highest bracket is 37%, and only the dollars above ~$520k are subject to that 37% rate. Even including state income taxes, only persons making more than $600k are subject to the highest theoretical rate (which is below 50%), and even then only on the dollars earned in excess of $600k.
So, for example, if Superstar BBaller earns $601k in wages for playing for the LA Hoopers, he pays $58k in taxes to CA (the mathematical total of the progressive lower-taxed brackets), plus $123 for the $1k over $600k. He pays the feds approximately $150k for the lower-taxed brackets, plus $30k on the $101k in excess of the $520k threshold for the highest-taxed bracket.
And even that example overstates the taxes he pays, since it excludes deductions, tax credits, state tax credits, etc., that would lower the actual tax paid.