To get clear - you are asking for reasons why you should listen to reasons? It seems like the reason you ought to listen to a reason is whatever is making you ask for reasons in the first place.

Or, to put it more extensively:

There's no rational argument anyone can give you to make you abandon your irrationality, because being irrational just means being non-responsive to rational arguments.

However, it sounds like you are being a little duplicitous here. You are asking for reasons to listen to other reasons. So it looks like you are committed to being rational (why else would you be concerned about asking for reasons?) but you still wants to ignore certain rational arguments, which is a paradigmatically irrational action.

This would be like refusing to believe that 2+2=4 even after agreeing that 1+1=2. It's true that you could say things like "why should I believe 2+2=4?" and "why should I believe the reasons you give me to explain that 2+2=4?" without also saying "why should I believe 1+1=2?" and so on. But this would be silly. It would be clear that for no good reason you've simply refused to believe in some parts of math rather than others.

Now, just because it's silly doesn't mean people won't do that. People are not robotic rational machines. People are not even like Spock. People are irrational constantly and consistently. We have good models to predict how and when people will be irrational in certain experimental situations, in fact. And we also have good reasons to think that you will be irrational in this case. You wants to keep eating meat and spend your money on yourself. Eating meat is easier than not eating meat. Spending your money on yourself gets you more cool stuff than spending it on others. So you have a personal stake in irrationally refusing to listen to reasons to be vegan or to give to charity. People are often quite irrational when it serves their interests.

So, just like we have good ways to explain people who irrationally refuse to believe in global warming (it would require them to act in more environmentally friendly ways) and ways to explain people who irrationally refuse to believe that there is no god (it would require them to face uncomfortable truths about mortality and providence) and ways to explain people who irrationally refuse to believe that their child did something wrong (it would require them to alter their extremely positive evaluation of their child), we have ways to explain people who irrationally refuse to go vegan even when presented with compelling arguments in favor of veganism (it would require them to stop eating meat) or people who irrationally refuse to donate to charity even when presented with compelling arguments in favor of donating to charity (it would require them to spend less money onthemselves).