500 years ago would be 1514, and there really wasn't much that was really science at that time. Science as we know it pretty much got going in the 1600s. Since then, we really haven't had all that many established scientific principles overthrown, so I'd say far less than 99%. Newtonian gravity turned out to be a very useful approximation, not so much wrong as incomplete. Electromagnetic radiation was partly understood in the 19th Century, and it turns out that that part was not sufficient to explain everyday phenomena (such as black body radiation). The main wrong thing about it was the luminiferous aether, and scientists in general were not comfortable with a thoroughly rigid medium that didn't affect anything going through it but light.
I don't know who you're talking about as "people". Scientists, in my observation, are very aware that they don't know everything, and generally subscribe to the attitude you recommend, only with fewer words. How much have you observed what you call being proven wrong ending people's careers?
I suspect you're mixing up scientists, science journalists, and science fans here.