If these large startups with crazy valuations are now in danger of not being able to raise a bigger round to sustain their burn rate, and the crowd mentality of

If these large startups with crazy valuations are now in danger of not being able to raise a bigger round to sustain their burn rate, and the crowd mentality of VCs sour, how realistic is it to expect any of these companies built on lack of due diligence in testing out the viability of their ideas to last? For example: startups delivering food. nobody done it before because everyone knew it was dumb unless you owned the entire delivery chain, and even then the margins were razor thin and they convinced bunch of VCs that an Android app was going to fix the broken business model.