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There are some who've lost their faith in democracy.
Literal
Democracy [toward-に対する] trust [object-を] lost person [topic-も] exist.
The ~もいる pattern ('there are also people who…') introduces a subset: 'some people have X-ed.' に対する is the noun-modifying form of に対して ('toward'), here letting 信頼 ('trust') take 民主主義 as its target: 'trust toward democracy.' 者 is a formal/literary word for 'person,' more clinical than 人.