But you said "I don't understand why anyone in their right mind would go to the trouble of making their product open-source." The "trouble" of going open source is the same trouble as any other business expense, whether that is developer time, security audits, etc. If that's Gitlab's business model, and open source really was their only choice for a sustainable business model, it's not hard for me to understand why they went open source. Your phrasing only makes sense if they were doing something they didn't need to do.