I'm almost thinking hard startups shouldn't exist. If a startup is considered hard, what is making it hard. Probably ecosystem / infrastructure. Maybe a good approach would be to ask the founder why timeline is so long or will cost so much. Once they answer those questions, ask them to build an "easier" startup that will be able to sustain itself and can (eventually) partner with the "hard" startup, which will only be launched once it becomes easy.

And I'm not saying do something different. I'm saying the "easier" startup would be built as a means to enabling the hard startup.