Even without touching customer funds the FTT token thing seems quite wrong to me.
And based the infamous Matt Levine interview, it was at best a legit ponzi exchange, according to what Sam himself says about the things being traded there.
Well yeah the FTT token thing was a bit iffy if not really a ponzi scheme. Exchange tokens go on - you can still get Binance token or Kucoin token if you like and they tend to work as a sort of equity benefiting from income from the exchange. But not exactly equity and kind of subject to manipulation and the like. Where FTX sinned was treating its FTT tokens as an asset on the balance sheet worth billions when they were not worth that.
The famous Matt Levine interview was about yield farming which as far as I know SBF didn't actually do but which he provided a striking explanation of. While that is Ponzi like it's a bit of a disservice to call it a Ponzi as it's actually rather more cunning and was the basis of most of the 'distributed finance' boom and bust.
But yeah if he hadn't been caught, he'd be doing well now.