The hardest part of building a SaaS has completely changed. A few years ago, building the product was the hardest challenge. Today? AI and vibe coding have made it possible for almost anyone to build and launch a SaaS in days. Now the hardest part is generating sustainable revenue. Here's what I keep seeing: Someone builds a product with AI. Buys a domain. Launches within a weekend. Prices it lower than everyone else. Gets some initial customers. Revenue slows after a few...