[bet] bottom dollar

to be absolutely sure that something is true

The origin of the idiom "bet bottom dollar" is not precisely documented, but it likely emerged in American English in the late 19th or early 20th century. The phrase draws on the notion of someone being so confident or sure of something that they would wager their last dollar, which is the "bottom dollar," on it. This expression is used to convey a high level of certainty or confidence in the outcome of a particular situation or statement. Essentially,

I would bet bottom dollar that she'll win the singing competition; she's incredibly talented.
He's a reliable mechanic, and I would bet my bottom dollar that he'll fix your car without any issues.
I'd bet my bottom dollar that the team will win the championship this year; they've been on fire lately.
After all the effort he's put into his business, I'd bet my bottom dollarWhat is the origin of the idiom "PASTE THE IDIOM HERE" and when to use it?that it's going to be a huge success.
She's so dedicated to her studies that I would bet my bottom dollar she'll graduate with honors.