For an initial production run there are a lot of fixed setup costs. Just from my gut feel 5000 units is just barely off the NRE (non recurring engineering cost) 'knee'. (And the manufacturing learning cost knee) Less than 5000 units the NRE costs start to dominate your out the door manufacturing price. So at 2000 units that might be 50% to 80% higher per unit than at 5000 units.
Also people often forget about your suppliers management, accounting, and sales overhead. That means that they will have minimum orders below which they don't make enough money justify the overhead of shepherding your product through their shop. For Chinese suppliers 5000 units appears to be typical because lower volumes are typically on-shored. On shoring is going to increase your costs by probably 30%.
You might ask the other question, why not 10,000 or 20,000 units? Answer is that starts to be a huge chunk of money for something that isn't proven.
So ans: 5000 because less the NRE kills you. And you'll have to on shore production. And no more than that because otherwise your initial production costs becomes the dominant part of the investment risk.
Also people often forget about your suppliers management, accounting, and sales overhead. That means that they will have minimum orders below which they don't make enough money justify the overhead of shepherding your product through their shop. For Chinese suppliers 5000 units appears to be typical because lower volumes are typically on-shored. On shoring is going to increase your costs by probably 30%.
You might ask the other question, why not 10,000 or 20,000 units? Answer is that starts to be a huge chunk of money for something that isn't proven.
So ans: 5000 because less the NRE kills you. And you'll have to on shore production. And no more than that because otherwise your initial production costs becomes the dominant part of the investment risk.