I have been self hosting since couple of years, yes I got very very interested in self hosting my apps, away from the cloud overlords, but the major issue is the network.

You'll need business internet plans with redundancy and based on locations that might be prohibitively expensive. Some startups might even require their own AS numbers.

Also the connectivity to the data centers or cloud infra like WAF , CDNs etc will be definitely worse compared to cloud instances. Then comes firewalls, their configuration and their redundancy.

These things will matter if you're serious about your SaaS.You could definitely co-locate, but that's another cost, then comes the redundancy of everything, from servers, to disks to network (routers and switches etc).

I personally believe that modern hardware is pretty reliable and doesn't need redundancy in every layer, but most people won't agree with and when startups have enough money, this doesn't matter to them.

I think the only reason the common public is unable to start SaaS is handling and managing these problems. Redundancy costs a lot. And many startups don't want to deal with it even if it'll help them in long run. They just gather enough cash and throw at the overlords.

I do hope that the general infra should improve so that can properly host their own.

Nevertheless I'm still trying to start something in SaaS space and self host from my home...