Start small and niche. You need to gain trust in consumers to be successful.
Moderating and staffing a giant website with 1,000 different functions will be next to impossible unless you have the knowledge base and investment to do so.
Go look at where CraigsList was back in 1998 compared to now. They were much more limited back then.
Look at Google. They didn't open their company with search, adwords, GA, GSC, Google Suite, Google business, cars, Google Developers (the resource), the forum, Gmail, etc. (the technology wasn't around back then for all that but you get the point). if they did, they would have run out of money before they made any.
A company doesn't start as a fortune 500 company. It starts by fulfilling a market need to the consumer.