Everything I learned building rental marketplaces (and why I stopped doing it from scratch)

I've built three rental marketplaces in the past two years. Every single time, I told myself "this time it'll be faster." Every single time, I was wrong. The first one took me about four months. The second one, three months. By the third one I realized something — I was spending 80% of my time on stuff that had nothing to do with what made each marketplace unique. The same 15 problems, every time Here's what ate most of my time, in order of how much I underestimated each one: Messaging. You think it's just a chat box. Then you need real-time delivery, read receipts, unread counts in the nav, conversation lists, notification emails when someone doesn't reply, and suddenly you've spent three weeks on "just a chat box." Reservations. Date picking UI, availability calendars, booking status workflows (pending → confirmed → active → completed → cancelled), conflict detection, timezone handling. Every edge case you didn't think of shows up in production. Auth. Not just login/signup. Email ver