In my experience, maybe 2% of software engineers are incentivized more strongly by positive social change than by money or fame. These are the idealists, like Richard Stallman and former members of OLPC, who are often ridiculed by the rest of the community. Until the academic and governmental infrastructure is able to put anywhere near as much money into CS research as private industry, the majority of technologists will (have to) be driven by the desire to make money.
For all the talk of how doctors make a lot of money, the reason they do is that so few are both qualified and willing to take the long, grinding road through 8 years of medical school and residency, $200k in debt, and 80 hour work weeks, with fierce competition at every step of the way. According to the med students I know, if you aren't inspired by some higher calling it's almost not worth it because you won't make it through.
In my experience, at least in US, less than 1% of medical students go into the field "to help people." In fact, nowadays saying you want to become a doctor "because you want to help people" sounds almost cliché. Most of them do it either for money, social status or because that's what their mom wants them to do. And while it's true that very few programmers are "incentivized by positive social change", many of them do it because they find it interesting and fun in some way.
And medical education doesn't have to be structured that way at all. Medicine could be like engineering, where you start on day one of your undergrad and take 5-6 years in an average university setting, and 80 hour residency programs are just counter productive.
For all the talk of how doctors make a lot of money, the reason they do is that so few are both qualified and willing to take the long, grinding road through 8 years of medical school and residency, $200k in debt, and 80 hour work weeks, with fierce competition at every step of the way. According to the med students I know, if you aren't inspired by some higher calling it's almost not worth it because you won't make it through.