A self-modifying AI is built to serve humanity. The builders know, of course, that this is much riskier than it seems, because its success would render their own observations extremely rare. To solve the problem, they direct the AI to create billions of simulated humanities in the hope that this will serve as a Schelling point to them, and make their own universe almost certainly simulated.
Plausible?
Saying that "one can" do something in MWI is misleading because there are many "ones". If you don't commit suicide, there is a "one" who won and other "ones" who lost; if you do commit suicide, there is a "one" who won and the others are dead. Committing suicide doesn't cause you to win because you would have won in one of the branches in either situation.
Well, OP's argument would have many "ones" as well. Every simulated copy of me should count at least as much as it counts in MWI.