If they are insolvent, then not everybody can get their money back, which means that you should take your money out immediately no matter what you expect other people to do. It follows that you can expect everyone rational to do the same. It's not that anyone chooses to "make" it fall apart, it's that everyone who finds out their secret should independently participate in making it do so and that reinforces itself.
This contrasts with a bank run on a solvent institution, where you only need to rush to get your money if you think other people will too and they will fail due to lack of short term liquidity.
If they are insolvent, then not everybody can get their money back, which means that you should take your money out immediately no matter what you expect other people to do. It follows that you can expect everyone rational to do the same. It's not that anyone chooses to "make" it fall apart, it's that everyone who finds out their secret should independently participate in making it do so and that reinforces itself.
This contrasts with a bank run on a solvent institution, where you only need to rush to get your money if you think other people will too and they will fail due to lack of short term liquidity.
That's how I imagine the difference anyway.