[evm9]

There are many, many reasons that a startup may have failed (or is failing) and there still may be a product-market fit.

Some products & markets require you to go out and get users more than others, and they may not have done that.

It's on a case by case basis, just be sure to get validation for your project. Make sure that you're making something people actually want, and if they want it, how much they will pay for it. Can't stress it enough how important it is to go out and talk to potential customers, ideally hundreds, and figure out if they'll pay and tell their friends about it.

Marketing is important -- having a good landing/marketing page, getting press, etc. But at the end of the day the product is what will create retention. Looks get the first date, but your personality is what will get you the 8th date.