In the optimal strategy for Thief 1, he gets 98 gold coins.
Thief 1 needs to propose a distribution that ensures his own survival, as well as gaining the approval of at least one other thief.
Thief 1 can propose to take 98 coins for himself and distribute 1 coin each to Thieves 2 and 3. This gives him the majority of coins and ensures the survival of Thieves 2 and 3.
Thieves 2 and 3 would likely vote in favor of this proposal since they are getting more than 0 coins and they also prioritize survival.
Thief 4 would vote against the proposal, but since Thieves 2 and 3 together form a majority, the proposal is accepted.
Thief 1 will get:
= 100 - 2
= 98