Something that is allowed in a penny

The Gemara says that vows are something that is permissible because they are in question. We see that even if the permission involves an act, it is considered something that is permissible. Although the name of the act is to go and ask for money, here it is about giving money. As far as I understand, this is not called something that is permissible, since he has to take money out of his pocket to make it permissible. The reasoning for something that is permissible is that it is not permissible for him to eat it with prohibition if he can eat it with permission. But if he has to spend money on it, it is not considered permissible for him to eat it with permission. And in a slightly different way: the whole idea of ​​canceling by majority is to save money. The Torah does not require you to give up the permit just because of fear of prohibition unless the prohibition is greater than the permit. And if he has permission, then he does not lose anything and there is no reason to allow him. But if he has to spend money to eat it, then he does lose money, and therefore it is unlikely that he was forbidden in such a situation. But here we are talking about a prohibition on a vow (it is a vow that benefits from the thing), and prohibitions on vows in general are something that is permissible. Therefore, the bottom line is that such a thing is permissible, not because it can give charity, but because it can be questioned about it.