As the employees are bringing their own device so they can misuse this device by sharing the sensitive corporate information with other people.
Um, you're stating that employees bring their devices to work for corporate espionage... First of all your sentance structure is wrong, second you can't just jump into a wild statement like that.
Even the corporate and the personal information gets so much co-mingled on devices that it creates the security challenge.
Like what?
The employees are bringing their own device for corporate work which increases the cost for employee itself.
Bad structure. Logically, this doesn't help your point. You framed your argument from the standpoint of corporate policy... doesn't this lower business costs?
I've very lost with the last half of your essay... You framed the beginning as "BYOD is bad", then you list reasons its good...