。
She's not foolish enough to spend all her money on kimonos.
Literal
She [topic-は] kimono [on-に] money [object-を] all use-up [to the extent-ほど] fool is-not.
~ほど馬鹿ではない ('not foolish enough to / not so foolish as to') uses ~ほど to set the threshold of foolishness and negates it. 金を全部使ってしまう ('end up spending all the money') uses ~てしまう for the regrettable outcome of spending everything. The sentence defends her intelligence by denying an extreme scenario.