Why would you immediately "make an impact" as soon as you switch jobs though? If you're not taking that new position, somebody else will be and I'm not sure you're that unique enough to do something totally different from the job done by that other person. Plus, it's usually the case that the longer you stay, the more influence you gain, and I don't think you can effect changes in a new organization rapidly, unless you're hired as a CEO or something. Maybe the only thing you get by switching jobs is to actually have products that you touched reach more users, but I don't think that equates to "improving the lives of others". Have you actually switched many jobs and felt happier afterwards? I can't really get your reasoning.