There are several psychological and emotional factors for citizens to think that politics does not change, that there is no candidacy worth running. That everything is always the same.
First, there is confirmation bias, which is the tendency to selectively seek, interpret, and recall information to confirm existing beliefs. When people have had negative or disappointing past experiences in the political arena, they may look for evidence that confirms their belief that things will continue to be the same. For example, a terribly tense debate can confirm that the policy is not going well and that it is not credible.
Second, there is the concept of learning by association: if what many people have learned about politics is that lies and promises are not kept, they are likely to think, by association, that their future political experiences will be similar and therefore can develop an attitude of distrust and boredom.
And boredom is an emotion. And a sign of the loss of hope for a possible change in politics and society. Thinking that everything is the same again means not differentiating the candidacies, one from the other. And it is also a symbol that things are not being done correctly, that polarization makes the challenge of governing impractical, that there is no space to reach the less politicized population, that legitimacy and trust have been eroded in the institutions. Because those politicians are no longer trusted, because they are not enthusiastic, because they do not manage to persuade or convince that they are indeed different from the rest, that they are not the same as always.
Then the most plausible options can be: voting with your nose covered for whoever is considered less evil, abstaining, exercising a punishment vote, voting for a party that represents a useful and testimonial vote for this motivation, even if it is useless to govern, or use the last resort: the null vote.
The reasons for voting, and the mechanisms that lead to voting, remain complex and sometimes incomprehensible. But we do know that emotions influence motivation and political commitment and (the negative ones) can lead to adopting attitudes of apathy, disinterest or even rejection.
