[Laforet]

Most non-fastfood resturants actually price their food at or near cost after the overheads are factored in. Profit actually came from (overpriced) beverages and drinks. If a startup is to compete with them there is no way for them to make much money.

[Fomite]

"If a startup is to compete with them there is no way for them to make much money." Selling overpriced drinks? If a startup is in an area where "there is no way for them to make much money" then what the hell are they doing there?

[Laforet]

The line of thought was probably that they may reach a scale that can overcome these overheads since they don't have to pay rent or hire full time staff for every outlet.

It makes sense if you consider very early examples like Amazon which took more than 10 years to become profitable. Unicorns like Twitter and Dropbox are not profitable and are unlikely to become so in the near future, but they have reached a scale that their finances are relatively secure for now.