This is the last straw.

You can't make bricks without straw

It was the final straw for a lot of voters.

It was the piece of straw that broke the camel's back

An event like this can be the proverbial straw that breaks the market's back.

It's the straw that broke the camel's back for some of them. If you're somebody who was already down to the last thread of survival, just trying to keep the bills paid, this will leave you flat out.