The hard part in building a two-sided market is getting users AND buyers on your platform. This generally means epic shit-tons of brand marketing to end users, which is where a lot of those millions of VC dollars go. There's really no way to get brand recognition otherwise -- you have to spend some ad dollars to inform users of your product. Ad spend is a zero-sum game from a competitive lens, so if your competitors are out-advertising you, they're going to win. And yes, this is why companies tackling two-sided markets focus on user acquisition over profitability.

You were also trying to fix the wrong problem. Focusing on the user experience is the right call, but your mistake was saying "fuck this, the distributor model is so fucked we can't do it". Ok, if the supply chain of a specific industry is super-expensive, your business model should be to streamline it by going direct and undercutting everyone else (this is what Uber did).

You needed to build a new distribution model. It's fair to say "I'm a college student and don't have time to fix this big problem" -- which is fair, supply chain problems like this are usually best left to people with experience in them or at least a passion for solving them.