Your one vote is arguably not worth the effort, yet if everyone decides that, it has great consequence.
If everyone decides to do what, to specifically refrain from voting, or to do a sober cost-benefit analysis of voting?
If people voted rationally, they would put far more value on participating in a civic rite and feeling like their voice is heard, and very little value on the prospect of changing election outcomes. Perhaps many people already think this way, explaining why about half of eligible voters don't bother.
If no one cared about rites and signaling, far fewer people would vote, and at some point an individual vote would have enough potential power to make it worthwhile to do the research and make the effort to vote, so the system would not collapse.
Doing something for the public good often looks irrational on an individual basis.
Can you give an example of this outside of voting?