Assume Joe (MFJ) has $350,000 in net income from his sole proprietorship in 2022. His SE tax would be calculated?

Why is there a need of Lessing the first 7.65%? is it because he can deduct that portion as business expense?

Self-Employment Tax Calculation \begin{tabular}{lr} \hline Net Schedule C earnings & $350,000 \\ Less: 7.65% & $26,775 \\ Net earnings for self-employment tax & $323,225 \\ OASDI tax due on wage base =$147,00012.4% & $18,228 \\ Medicare tax due =$323,2252.9% & $9,374 \\ Additional Medicare Tax due =($323,225$250,000)0.9% & $659 \\ Total & $28,261 \\ \hline \end{tabular}