Ait could be that this fee close to $100k was paid by intention to convert bitcoin from criminal activity into miners coins which are usually seen as innocent virgin coins.
Only the coinbase reward of miners count as virgin coins, the transaction fee is obviously from an address and has been involved in multiple transactions before then.
How to investigate this? If the transaction was not in the mempool of the most nodes or if the transaction wasn't in orphaned blocks at similar time then it's very suspicious that the fee was given to the miner by intention to launder the coins.
Crime is not the only reason why someone would want to obfuscate the trail of transaction. Privacy and freedom are essential parts of Bitcoin and one can take extra effort at maintaining that.