I think that you capture popular feelings very well here, including the contradictions within them (for instance, if any alternative is worse than capitalism, why do people often add that "anyway you can't win"?). I believe that the feeling that "anyway you can't win" is the most debilitating one in the long term.
Feelings of this sort are of course in part caused by objective difficulties of winning anything under capitalism, but people resist getting involved in 'activism' not simply because of the above feelings you describe so well. I think that many people don't get involved in 'activism' because in a whole lot of cases 'activism' is done for the sake of keeping 'activists' active, not really to _win_ anything worth winning. There are many reforms that are winnable, but oftentimes so many compromises are made _ahead of time_ to avoid looking 'unrealistic' that the resulting 'goals' of reforms don't capture popular imagination at all. Why should anyone waste time running around collecting signatures, handing out leaflets, organizing, holding rallies, marching, sitting-in, etc., if the objects of reforms are petty, compromised, full of loopholes, hard to understand due to vague language or complex schemes, and so on?
Yoshie