Public perception can be strange. For the past couple of days, different networks have been playing shows relating to the 9/11 attacks. The one about the hunt for bin Laden showed parts where people considered him a hero, and I think one I saw a while back said he had a lot of philantrophy and infrastructure building efforts before he started focusing on terrorism.
That first one also had info on him justifying an early bombing as “they weren’t in the Mosque like they should have been, so I did them a favor by killing them”, even though there were women and children that were killed, a violation of what’s laid out in their religious text. Any time you start classifying people by whether or not they are a “true” believer, they’ll always fall short because they’re human, and the ones doing the classifying and judging conveniently use that as their justification even though they’d also fall short if they were similarly judged.
For other people, it’s the passage of time that grants them a favorable light in the eyes of history. Andrew Carnegie and John D. Rockefeller weren’t saints, but there’s favorable parts of their life. Bill Gates will probably be the same way via the Bill and Melinda Gates Foundation and other efforts.