Temporarily I guess it would drive the price down, and then production would adjust to meet the lowered demand.

Think about it this way: if the number of meat eaters halved overnight, meat would be really cheap for a while, then a bunch of producers would go out of business and prices would rise again, and prices would stabilise again once production was half what it used to be.

You're assuming that the remaining meat eaters' consumption would remain constant. It would almost certainly increase (I know mine would increase, or rather, I'd eat more expensive cuts of meat more often, like cote de boeuf); and I'd expect substitution effects - it's hard to predict what the final outcomes would be.

Lobbying for regulation would be a more effective use of your time. Or something that converts individual action into collective action with an enforcement mechanism, like group shaming - but it's hard to get these to spread reliably.

I think it's unlikely that the remainder of the population would double their meat consumption.

The more obvious failing point might be the fact that as the price of meat goes down, people (e.g. in developing countries) who weren't able to afford meat now can afford it and so consumption goes back up, so actually the production doesn't go down, instead standards drop as the consuming population becomes even less discerning as to the way the meat is produced. Grr.

What if I don't want to engage in group shaming? What if I don't want to tell other people what to do?

Lower price signals the suppliers to find different work to do.