You can make systemic changes to reduce the amount of animal products that people consume. For a start, you could stop subsidizing them. For the long term you

You can make systemic changes to reduce the amount of animal products that people consume. For a start, you could stop subsidizing them. For the long term you could fund a massive meat replacement research project. (Though I disagree with the OP that this is the biggest issue, it is a large enough issue that it's worth tackling it, and certainly larger than streaming video.)