This is about as bad an argument as saying that voting is pointless because one individual vote is not going to change anything. Individual purchases summed up amount to a lot.

If it was comparable we wouldn't need regulation to protect consumers.

Voting is answering a direct question. Yes or no with direct results. Your purchase isn't like that, they're not votes. Business behavior is decided by what is more profitable. That also assumes there is a choice to be made. There's nothing you can do if all options behave the same way.

Your vote doesn't matter if the two options you vote for are the same. Often not true for politics, frequently can be true when making purchases