Combat student loan interest?

Hello everyone, I am 22 years old and am going to dental school. I have worked hard to do this but the debt from it is insane. I have now begun my finance journey by starting and maxing my Roth IRA out as well as opening a brokerage account. I heard from channels that there was a dentist that had taken his student loan money and put it in a brokerage account to combat the interest. They had stated that they made enough to pay the interest and make profit. I’m curious of how taxes would have played a role in this, especially capital gains taxes when withdrawing or even income tax. Does anyone know anything about this and could shed some light?