Wikipedia is not funded by ads for example. Lots of other sites neither.

So I would say, not the whole internet would go away without ads, but probably the worst parts and what remains is worth visiting.

But how many Wikipedias can there be?

They got funding because they are large and have reputation behind them.

If you tried starting up a new Wikipedia to compete, guess he much non-advert funding you'd get?

Look at how quora tried and failed hard, and have to sell out to survive. Look at stack overflow these days?

I don't have the number offhand, but Wikipedia did exactly that kind of startup competing with online encyclopedias.

"Look at how quora tried and failed hard"

They made lots of bad choices, leading to users (including me) leaving the plattform.

And in general I don't think that you need that many wikipedias, my point was, that donation funded websites work -> if people want it to work.

You don't need resources if you are small and unknown. Run it at your house until you have a few thousand users, and then move to something like Hetzner (if you're one of those Swiss people with 25 Gb/s Internet, skip step 2). If I'm interpreting their grafana[0] right, Wikimedia gets ~20 edits per second and usually peaks less than ~200k requests/second across all projects, and it looks like traffic has not exceeded 7 Gb/s over the last 90 days across all data centers. Even the largest projects are not a lot from a technical perspective these days.

[0] https://grafana.wikimedia.org

When I was a teenager, I found and installed Apache. WordPress apparently had existed for a year or two, but I didn't hear about it for several years after. I memorized my IP address and would link people to that, and never bought a hostname or anything.

If you just want to host a blog and maybe dabble in PHP, Apache works great. These days as an adult who programs professionally, my personal site is just a directory that I point nginx to with xhtml/xslt/css files that I hand edit + things like photos. I do have a domain name these days, but it's not like you need one. If you wanted something to be permanent to avoid link rot, you should want browsers to support ipfs so you could use that.

there's always dynamic dns, too

Maybe someday ipv6 will become widespread and we can all have thousands of static IP addresses.

Can we agree that "must be able to install apache" is not a good requirement for adding content to the web?

It's not a requirement; it's a $0 option. You could also pay someone a few dollars or befriend a local computer nerd. My memory is fading now, but I think ISPs used to offer web hosting and email as part of your Internet package, so they could always bring that back (I think they still give you email). Once upon a time, Windows came with a web server. You could imagine that sharing a folder on the web could be as easy as it is (was?) to share a folder through SMB (just open folder properties, click "Share", and give it a name).

You asked what a free internet would look like without ads, but you need to keep in mind that ads have distorted the market that we have today. Even today, it's easy for a curious teenager to set up a web site for free on their computer, and it could be made even easier if the demand weren't being satisfied by people dumping onto markets.

Nowadays, you can get a free VM from some providers (GCP) and there are lots of sites where you can deploy a static website for free (github pages). I'd argue deploying something for free is easier than ever.

Things were already free before the advertising boom, internet was not really worse twenty years ago