Some software. Do you think companies catering to public sector or the enterprise are high margin in the first few years?

Consumer apps can often get away with scaling ARR and slow incremental growth, but many of these are only feasible due to the existence of VC backed SaaS.

It also has a high start up cost—meaning the owners would have to be able to support themselves, their families, and pay for whatever costs the company needs until people are willing to pay for the software. That is, if such a day ever comes.

Not necessarily, you can take another job to pay the bills. Or if you're in the UK we have dedicated benefits schemes to fund people starting a business.

“Relatively small number of subscriptions” may not even pay for a skeleton staff, let alone leave a nice profit afterward.