Just spit-balling here, but writing software can be pretty non-capital intensive. You need a computer, and your time. Hardware costs money. You need to buy tools. You spend money on raw materials. Spend more time and money to turn those raw materials in components. Spend more time assembling the parts. Find out there is an issue with widget A not working with widget B. Redesign B, buy its raw materials, have it machined again. Finally build first prototype after 6 weeks. Discover its flaws. Spend some more money to iterate. Wait another 6 weeks. Oh, and manufacturer Z says part C is a last-time buy. Would you want to buy 5,000 units now?