Learn English – Why do we say “Fever broke”

Broke is an old form, and nowadays informal, use of broken. If we look in the OED we can see that one of the meanings of break is:

11a. To ruin financially, make bankrupt (a person or bank).

[First recorded in the 17th century.]

11b. To become bankrupt, to ‘fail’ (commercially).

[First recorded in Shakespeare (Merchant of Venice Act III, sc.1).]

he cannot choose but break.

The definition of broken with the meaning of having no money in the OED is:

Reduced or shattered in worldly estate, financially ruined; having failed in business, bankrupt.

[First occurrence of broken in this sense is recorded in 1593.]

(Shakes. Rich. II, ii. i. 257 The Kings growne bankrupt like a broken man.)

The first occurrence of broke is recorded in 1665:

(Pepys Diary 6 July (1895) V. 6 It seems some of his creditors have taken notice of it, and he was like to be broke yesterday in his absence.)

Broke means to undo, smash, tear etc. Here it's metaphorically picturing the ¤100,000 limit as being broken like an athlete breaking a tape. It's such a common metaphor as to have moved past cliché into a new meaning.

Broke into means to break something so as to gain access to something or somewhere (burglars break into houses, and in some jurisdictions this is a separate offence to both the vandalism and the trespassing entailed). Here the speaker is referring to the fact that they stayed within the ¤100,000+ region after this - they moved from one state to another, and stayed in the latter. It's a bit of a clumsy use though, to my mind.

Priorities about what counts as "failing at life", is another matter...