Why are  Multi-party democratic nations  prone to  corruption , sabotage  of Institutions by the CCP , ISIS  , etc. ?

Parliamentary Democracies like the U.K. and the U.S.A. have only 2 or 3 main political parties vying for political power  , in the public interests . But in Multi-party democracies there are usually a very large number  ofg political parties, with all kinds of mafias  controlling them for the mafia interests (not public interests) , by corrupting and criminalizing the  govt. officials, especially the Police, Revenue officials  , etc. Sooner or later, these officials and  the  poorer sections , religious groups,  come under the  influence of the  ISIS, Al Qaeda, etc.  eg.Lebanon , Iraq, etc.