Does one "always have to risk political dispossession in order to escape political dispossession"?

I think you are right in that most people need to risk compromising their beliefs in order to actively defend them. For an individual to successfully fight against political dispossession without collective mobilization is unheard of, and one can generally rely on the fact that individuals will have to compromise their values somewhere along the line when taking collective social action. It is possible for an individual to eschew any form of compromise, but it is rare for such an individual to find allies that would give them the strength to achieve their goal. In which case, without collective action, they will most likely be politically dispossessed.

Some people who may be an exception are highly charismatic leaders who can persuade people to align themselves with their beliefs (I'm looking at you, Jim Jones). However, attracting people to your cause requires its own form of compromise, as one would have to posture themself and express a specific persona in order to appeal to as many people as possible. For some, the real incentive is the feeling of power that comes from converting people to one's beliefs, rather than furthering their political goals.

It might also be worth looking at religion in general, as there are many different sects in Christianity which interpret the religion differently, with some sects strictly obeying traditional Christian beliefs and practices. In this case, they are not (typically) trying to achieve a political end, but they nonetheless have to come together and compromise on certain issues in order to maintain the strength of their beliefs against opposing factions.

I think the examples with Christianity, or religion in general is very interesting. With all the different branches of a main religion, there are always some aspects that are different from each other, and these differences will appeal to different people. Some branches are very traditional while others are very modern, within a religion, as long as the main doctrines are the same, I think people are able to find a branch that is comfortable with them, There will be compromises made but it does create a sense of community and strength against other groups.