They don't have their own ai, they have an ai frontend which runs preexisting open weight ai models.

Proton does have a lot of fans probably because they are the most well known 'privacy' company and a lot of people set and forget without reading into them.

they have their own ai

They don't make it:

https://proton.me/blog/lumo-ai

Lumo is based upon open-source language models and operates from Proton’s European datacenters. This gives you much greater transparency into the way Lumo works than any other major AI assistant. Unlike Apple Intelligence and others, Lumo is not a partnership with OpenAI or other American or Chinese AI companies, and your queries are never sent to any third parties. Our research and development will remain focused on open models, which we will continuously improve and augment.

Per discussions online, it seems to be a mix of small Mistral and Olmo models, and GLM for the max tier.

This'd be like arguing a company hosting database software to serve a product is a "database software company." They are a hosting some tool made by someone else, with a sticker.

they also have the most ridiculous brand fans.

Perhaps. I'm a bit scared of how much critical mass they have, TBH. But this does not make them an AI company.