Start a new game to play the Epsilon missions

The only reward you get from delivering the money is a tractor.

Because of that, it is generally recommended to just take the money for yourself. Not only do you get a return on your previous investment, stealing the money also happens to be part of the gold medal requirements along with killing all Epsilon security guards pursuing you. Add to it the additional challenge and the satisfaction from getting revenge after all the nonsensical tasks given to you up to this point, it's not difficult to see why it's preferable to just keep the $2.1 million.

After the mission is done you will receive a text message whose content depends on whether you stole the money or not. Surprisingly, nothing else will happen even if you steal the money (no crazy followers trying to kill you from time to times either).

You've finished the game. Outside of any activities you may have left (Strangers and Freaks, etc.) there is only the sandbox/open-world elements left to the game.