A fly-by-night businessman is someone who wants to make money very quickly, without caring about the quality or honesty of the service they offer.
INFORMAL adj ADJ n (disapproval)
...fly-by-night operators who fail to complete jobs.
Translation English Cobuild Collins Dictionary
1 cowboy (informal) dubious, questionable, shady, undependable, unreliable, untrustworthy
2 brief, here today, gone tomorrow, impermanent, short-lived
English Collins Dictionary - English synonyms & Thesaurus
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