Why are janissaries so expensive yet so weak?

Seriously i created an 10k janissary army and it eats money faster than any high tech army could have its cost is abbysmal about 20 ducats per month like wtf these dudes aren't even that strong???
I also have given them a privilage that makes them like %10 cheaper to employ but nah they still cost so much i am bankrupt with 2k on debt now.
Their %50 more reinforce cost outweights their %10 shock damage bonus.