I don't think any player should be saddled with being the "next Lebron". Superstars of Lebron's caliber come along every 20 years or so.
At the same time, I'm not sure that the Scottie Pippen expectations are any better. Pippen was a top-5 player who played elite defense and was very good to excellent at everything else.
Ben Simmons could have a very successful NBA career and still never approach Lebron or Pippen.
(As for the killer instinct thing, I think that gets overblown. Lebron has been accused of the same thing, deferring too much to his teammates. It's only in recent years that he's become regarded as a killer playoff performer.)