[RcouF1uZ4gsC]

> - who pays for the service (ads? users pay? Average user will never use a paid service if a free one is available) - how to resist attacks against the algorithm (Google has been fighting spam for decades)

The solution for o both of these might actually be a paid service. If you have a paid service, there is a possibility of it being profitable with much fewer users. As an example, let’s say you have 1,000,000 users at $10/month, that is a $10,000,000/month which might be enough to run the service and provide a comfortable profit.

With regards to the spam issue, the fact that you have a small user base would be to your advantage. Because there are so many Google users, it is in websites’ economic interests to spend money to try to game the algorithms. With much fewer users, your paid search users may not be worth it for the sites to spend money trying to game your algorithms.

[avsteele]

It will still pay to put ads in to paying customer's feeds. It's more or less inevitable if the customers tolerate it. If you think that's impossible I'd point to how streaming services are now serving up ever more adds.

[Nextgrid]

The spam issue can trivially be addressed by implementing actual penalties for rule-breakers. If it takes a long time to acquire a good reputation & ranking on the search engine, you're unlikely to risk it by doing something nasty in fear of your domain, keyword or brand name being banned for a long time.