- Enron blew up in Dec. 2001. It wasn't until mid-July 2004 that Jeffrey Skilling and Kenneth Lay were finally arrested.
- The WSJ expose on Theranos was in 2015, Holmes wasn't indicted until 2018.
- Martin Shkreli's MSBM collapsed by 2012; he wasn't indicted until 2015.
Bernie Madoff is a notable exception: he was arrested 3 days after his Ponzi was revealed. But it's not comparable at all to SBF's situation: Madoff was arrested after he confessed privately to his own family; his sons immediately went to the police.
Whether SBF is getting exceptionally soft treatment will be easier to discern in retrospect, but it might be many months or even years before he's indicted.