FitzTheRuke
Legend
I don't think being curios and not listening to authority is evil (in or out D&D) as much as it is chaotic or something similar...
if an NPC tells me 'take this letter to X, don't open it and read it' I have about a 60/40 chanve where 60 is doing as i was told and 40 being taking a look... some of my players it;s closer to 5/95 but I wouldn't call any of them evil.... and being ambitus isn't being evil
You're right that being ambitious isn't evil - in itself - but that's not the only evil-like aspect that your stereotypical gamer (I'm honestly not talking about all gamers in all actual games, but the overall zeitgeist) plays with.
There's ambition, but there's also righteous indignation, selfishness, inflexibility, might-makes-right, irresponsibility (on the fate of NPCs), dishonesty, cruelty, obsessive control issues, narcissism, remorselessness - the list of evil traits on display goes on.
It's an unfortunate side-effect of the power fantasy.
Again - absolutely - there are plenty of thoughtful players who can play kind heroes, but nearly all players can fall into behaviour that could be considered evil from time-to-time.
Like I said earlier, it's where the "murder-hobo" stereotype comes from.