1 delegate can ignore blocks from the other 100 and thus fork the network without bribing anyone, but that doesn't gain him anything.
51 delegates all ignoring blocks from the other 50 doesn't gain them anything either. Their fork will have 51 delegates, but the honest fork will quickly replace them and have 101 delegates.
Chain of 1 delegate will be very short and ignored.
51 delegates ignoring blocks from other 50 get the bribery money. How the honest fork can win if its chain is shorter?
I still fail to see why on earth anyone would jeopardize their reputation and future pay for a laughable 1% bribe (spread out over time as well), and more importantly how you expect to be able to bribe >50 delegates without a single person refusing and blowing your scheme open.
To me this whole scenario is so far fetched I don't understand how it's gotten to 4 pages of discussion.. You're saying the delegate will use 80% of his pay in order to stay elected, but that's just not realistic so in reality you'd have someone paying more to stay in than what they're earning by staying in. So then what would be the point of doing all this?