I think people want closure.  They want to see the crooks behind this scheme in jail.  Hopefully the police will eventually catch them.  Victims just need to continue making noise-- the squeaky wheel gets the most attention.

Individually, many people made small investments.  At this stage, it is not worth their time and energy to do much more, so it is logical to move on and focus on other goals.

As an alternative, people can spend time and/or money towards the mission of finding the crooks involved, but many people know when to cut their losses.  Even if the crooks are caught, the chance of recovering any money is slim.

There is always the possibility that one or more investors has a hobby of tracking down criminals.  In that case, they may throw more time and money towards this cause for entertainment value.

It's easy to say that you would not give up if you were in this situation, but this situation has drained energy from a lot of victims.