This is one of the reasons we have a refundable monthly “fee”. It allows us to start a project that has no money and (we hope) incentivizes the project to raise funds.
Starting with us with no money? No problem: you’ll pay us $29/month ($348/yr) and if you raise $5000+ in a fiscal year, we refund the $348 we earned in that fiscal year. (NB, $348/yr does not generally cover the actual cost of taking on a project but it covers some of it and it feels fair to us.)
I personally do not think you have an obligation to actively lose money and resources on a project that has not been able to raise any money and would argue that you are not leaving them hanging at all. If your business model does not allow projects to stick around and take up valuable resources while they figure out how to raise money, I think that’s okay to let them go.